docs: update Get Started documentation and navigation

- Introduce a new `index.md` file as the Get Started page, replacing `get_started.md`.
- Update `mkdocs.yml` to reflect the new file structure for navigation.
- Enhance the content of the Get Started section with an introduction to ArchiPy and installation guidance.

Author: HosseinNejatiJavaremi

docs/contributing.md

@@ -202,7 +202,7 @@ This section outlines the standards and practices for ArchiPy documentation.
 
 - `mkdocs.yml` - Main configuration file for MkDocs
 - `docs/` - Markdown documentation files
-    - `get_started.md` - Get Started page
+    - `index.md` - Get Started page
     - `api_reference/` - API documentation
     - `examples/` - Usage examples
     - `assets/` - Images and other static assets

docs/get_started.md docs/index.mddocs/get_started.md renamed to docs/index.md

@@ -120,7 +120,7 @@ plugins:
 
 # Navigation
 nav:
-  - Get Started: get_started.md
+  - Get Started: index.md
   - Concepts: concepts.md
   - Tutorials:
       - Overview: examples/index.md