refactor: rename cleanup_fonts.py to subtitle_fonts_cleaner.py and update README references.

README.md

@@ -34,8 +34,8 @@ pipx install fonttools
 Simply place the script inside the directory containing the `.mkv` files you wish to process and run it. You can also place the script in your personal `bin` or `PATH` folder to run it from anywhere.
 
 ```bash
-python cleanup_fonts.py
-# If in your PATH, simply execute: cleanup_fonts.py
+python subtitle_fonts_cleaner.py
+# If in your PATH, simply execute: subtitle_fonts_cleaner.py
 ```
 
 ### Folder Structure