Update documentation to match currently supported languages
The list of supported languages in our documentation does not match the languages we actually support in our IDEs.
Documentation:
https://docs.gitlab.com/ee/user/project/repository/code_suggestions/#supported-languages
Supported Languages:
- VS Code: AI_ASSISTED_CODE_SUGGESTIONS_LANGUAGES
- Visual Studio: LanguageManager
- JetBrains: SUPPORTED_EXTENSIONS
- Neovim: auto_filetypes
We should make sure that we have the updated list reflected in the documentation.