Add comprehensive documentation and code comments

This commit adds extensive documentation to the Mistral OCR CLI project:

- Add API.md with detailed API response format documentation
- Add CHANGELOG.md to track version changes
- Add CONTRIBUTING.md with guidelines for contributors
- Enhance README.md with more detailed usage examples and troubleshooting
- Add proper docstrings to all Python modules and functions
- Update requirements.txt with development dependencies
- Improve setup.py with better metadata

These changes make the project more accessible to users and contributors.

mistral_ocr/commands/version.py

@@ -1,6 +1,13 @@
 import sys
-
-VERSION = "0.1.0"
+from mistral_ocr import __version__
 
 def run(args):
-    print(f"Mistral OCR CLI v{VERSION}")
+    """
+    Main entry point for the version command.
+    
+    Prints the current version of the Mistral OCR CLI.
+    
+    Args:
+        args: Command line arguments parsed by argparse (not used)
+    """
+    print(f"Mistral OCR CLI v{__version__}")