Sweep(slow): update readme and env example file

[CNSeniorious000]

Details

There are some new env usages inside the code. Please search import.meta.env and update related information inside .env.example and README* files.

Checklist

• [X] Modify .env.example ✓ https://github.com/CNSeniorious000/free-chat/commit/c86c8b35f9da0d556bfab3658f49e50b400c7051
• [X] Running GitHub Actions for .env.example ✓
• [X] Modify README.md ✓ https://github.com/CNSeniorious000/free-chat/commit/892358b8ef9a20bf5c93ccebab060516830ac4a3
• [X] Running GitHub Actions for README.md ✓
• [X] Modify src/env.d.ts ✓ https://github.com/CNSeniorious000/free-chat/commit/3ee2206f813410e0a7e76e035d57b3102c9eba53
• [X] Running GitHub Actions for src/env.d.ts ✓