Add multilingual docs

[NikhilKalloli]

Hey @KoljaB
Addresses #152
This pull request significantly enhances the documentation for the RealtimeTTS library, adding detailed sections on configuration, usage, installation, and contributing. The most important changes include support for Multilingual docs.

Documentation Enhancements:

1. Created Documentation Structure:
   Added a docs folder containing documentation in two languages: English and French

2. Added mkdocs.yml:
   Configured the mkdocs.yml file to manage the documentation structure and navigation for both languages.

To run locally
pip install mkdocs mkdocs-material mkdocs-static-i18n
mkdocs serve
Also this docs can be easily deployed using github pages mkdocs gh-deploy
Please review the PR and let me know any enhancements

[NikhilKalloli]

Hey @KoljaB, Here are few screenshots for your referernce:
English:


French:

[KoljaB]

Looks great, thanks