update user guide

docs/user_guide.md

@@ -1,23 +1,40 @@
 # RenderCV: User Guide
 
+This document provides everything you need to know about the usage of RenderCV.
 
+## Installation
 
+> RenderCV doesn't require a $\LaTeX$ installation; it comes with it!
 
-After you've installed RenderCV with
+1. Install [Python](https://www.python.org/downloads/) (3.10 or newer).
+
+2. Run the command below to install RenderCV.
 
 ```bash
 pip install rendercv
 ```
 
-you can start rendering your CV.
+or
 
-Firstly, go to the directory where you want your CV files located and run:
+```bash
+python -m pip install rendercv
+```
+
+## Generating the input file
+
+To get started, navigate to the directory where you want to create your CV and run the command below to create the input file.
 
 ```bash
 rendercv new "Your Full Name"
 ```
 
-This will create a YAML input file for RenderCV called `Your_Name_CV.yaml`. Open this generated file in your favorite IDE and start editing. It governs all the features of RenderCV.
+or
+
+```bash
+python -m rendercv new "Your Full Name"
+```
+
+This will create a YAML input file for RenderCV called `Your_Name_CV.yaml`. Open this file in your favorite IDE and start editing.
 
 !!! tip
 
@@ -30,32 +47,100 @@ This will create a YAML input file for RenderCV called `Your_Name_CV.yaml`. Open
 
     === "Other"
 
-        1.  Ensure your editor of choice has support for YAML schema validation.
+        1.  Ensure your editor of choice has support for JSON Schema.
         2.  Add the following line at the top of `Your_Name_CV.yaml`:
 
             ``` yaml
             # yaml-language-server: $schema=https://github.com/sinaatalay/rendercv/blob/main/schema.json?raw=true
             ```
 
-After you're done editing your input file, run the command below to render your CV:
+## The YAML structure of the input file
-```bash
+
-rendercv render Your_Name_CV.yaml
+RenderCV's input file consists of two parts: `cv` and `design`.
+
+```yaml
+cv:
+  ...
+  YOUR CONTENT]
+  ...
+design:
+  ...
+  YOUR DESIGN
+  ...
 ```
 
-## Entry Types
+The `cv` part contains only the content of the CV, and the `design` part contains only the design properties of the CV. That's how the design and content are separated.
 
-There are five entry types in RenderCV:
+### `cv` section of the YAML input
 
-1.  *EducationEntry*
+The `cv` section of the YAML input starts with generic information, as shown below:
-2.  *ExperienceEntry*
-3.  *NormalEntry*
-4.  *OneLineEntry*
-5.  *PublicationEntry*
 
-The whole CV consists of these entries.
+```yaml
+cv:
+  name: John Doe
+  email: johndoe@example.com
+  phone: "+905555555555"
+  website: https://example.com
+  label: Mechanical Engineer
+  location: Istanbul, Türkiye
+```
+
+None of the values above are required. You can omit any or all of them, and RenderCV will adapt to your input.
+
+The real content of your CV is stored in a field called sections.
+
+```yaml
+cv:
+  name: John Doe
+  email: johndoe@example.com
+  phone: "+905555555555"
+  website: https://example.com
+  label: Mechanical Engineer
+  location: Istanbul, Türkiye
+  sections:
+    ...
+    YOUR CONTENT
+    ...
+```
+
+The `sections` field is a dictionary where the keys are the section titles, and the values are lists. Each item on the list is an entry in the CV.
+
+Here is an example:
+
+```yaml
+cv:
+  sections:
+    this_is_a_section_title:
+      - This is a TextEntry.
+      - This is another TextEntry under the same section.
+      - This is another another TextEntry under the same section.
+    this_is_another_section_title:
+      - company: This time it's an ExperienceEntry.
+        position: Your position
+        start_date: 2019-01-01
+        end_date: 2020-01
+        location: TX, USA
+        highlights: 
+          - This is a highlight (bullet point).
+          - This is another highlight.
+      - company: Another ExperienceEntry.
+        position: Your position
+        start_date: 2019-01-01
+        end_date: 2020-01
+        location: TX, USA
+        highlights: 
+          - This is a highlight (bullet point).
+          - This is another highlight.
+```
+
+There are six different entry types in RenderCV. You must choose one for each section and cannot mix types within a section.
+
+The available entry types are: `EducationEntry`, `ExperienceEntry`, `PublicationEntry`, `NormalEntry`, `OneLineEntry`, and `TextEntry`.
+
+Each entry type is a different object (a dictionary). All of the entry types and their corresponding look in each built-in theme are shown below:
 
 {% for entry_name, entry in showcase_entries.items() %}
-## {{ entry_name }}
+#### {{ entry_name }}
 ```yaml
 {{ entry["yaml"] }}
 ```
@@ -63,4 +148,102 @@ The whole CV consists of these entries.
 `{{ figure["theme"] }}` theme:
 ![figure["alt_text"]]({{ figure["path"] }})
     {% endfor %}
-{% endfor %}
+{% endfor %}
+
+### `design` section of the YAML input
+
+The `cv` part of the input contains your content, and the `design` part contains your design. The `design` part starts with the name of the theme. Currently, there are three built-in themes (`classic`, `sb2nov`, and `moderncv`), but custom themes can also be used (see below.)
+
+```yaml
+design:
+  theme: classic
+```
+
+Each theme has different options for design. `classic` and `sb2nov` almost use identical options, but `moderncv` is slightly different. Please use an IDE that supports JSON schema to avoid missing any available options for the theme (see above).
+
+An example `design` part for a `classic` theme is shown below:
+
+```yaml
+design:
+  theme: classic
+  color: rgb(0,79,144)
+  disable_page_numbering: false
+  font_size: 10pt
+  header_font_size: 30 pt
+  page_numbering_style: NAME - Page PAGE_NUMBER of TOTAL_PAGES
+  page_size: a4paper
+  show_last_updated_date: true
+  text_alignment: justified
+  margins: 
+    page:
+      bottom: 2 cm
+      left: 1.24 cm
+      right: 1.24 cm
+      top: 2 cm
+    section_title:
+      bottom: 0.2 cm
+      top: 0.2 cm
+    entry_area:
+      date_and_location_width: 4.1 cm
+      left_and_right: 0.2 cm
+      vertical_between: 0.12 cm
+    highlights_area:
+      left: 0.4 cm
+      top: 0.10 cm
+      vertical_between_bullet_points: 0.10 cm
+    header:
+      bottom: 0.2 cm
+      horizontal_between_connections: 1.5 cm
+      vertical_between_name_and_connections: 0.2 cm
+```
+
+## Using custom themes
+
+RenderCV allows you to move your $\LaTeX$ CV code to RenderCV. To do this, you will need to create some files:
+
+BURAYA FOLDER STRUCTURE GOSTERE, INPUT FILE I DA BELIRTEREK, YOUR_THEME SEKLINDE BIR DIRECTORY ALTINDA ZORUNLU TUM DOSYALARI GOSTER.
+
+Each of these files is LaTeX code with some Python in it. These files allow RenderCV to create your CV out of the YAML input.
+
+The best way to understand how they work is to look at the source code of built-in themes. For example, the content of `ExperienceEntry.j2.tex` for the `moderncv` theme is shown below:
+
+```latex
+\cventry{
+    ((* if design.show_only_years *))<<entry.date_string_only_years>>((* else *))<<entry.date_string>>((* endif *))
+}{
+    <<entry.position>>
+}{
+    <<entry.company>>
+}{
+    <<entry.location>>
+}{}{}
+((* for item in entry.highlights *))
+\cvline{}{\small <<item>>}
+((* endfor *))
+```
+
+The values between `<<` and `>>` are the names of Python variables, allowing you to write a LaTeX CV without writing any content. Those will be replaced with the values found in the YAML input. Also, the values between `((*` and `*))` are Python blocks, allowing you to use loops and conditional statements. The process of generating LaTeX files like this is called "templating," and it's achieved with a Python package called [Jinja](https://jinja.palletsprojects.com/en/3.1.x/).
+
+### Creating custom theme options
+
+If you want to have some `design` options under your YAML input file's `design` section for your custom theme, you can create a `__init__.py` file inside your theme directory.
+
+For example, the `moderncv` theme's `__init__.py` file is shown below:
+
+```python
+from typing import Literal
+
+import pydantic
+
+class YourcustomthemeThemeOptions(pydantic.BaseModel):
+    theme: Literal["yourcustomtheme"]
+    option1: str
+    option2: str
+    option3: int
+    option4: bool
+```
+
+Then, RenderCV will parse your custom design options, and you can use these variables inside your `*.j2.tex` as shown below:
+
+```
+```