Add wallet connect section to README.md

[verhovensky]

May be we should add section about editing config in src/configs/walletConnect.ts file?
Because if deploying without .env file and VITE_WALLET_CONNECT_PROJECT_ID variable inside it - the error occurs which says VITE_WALLET_CONNECT_PROJECT_ID is undefined.

I suggest the following:

1. Create account on https://cloud.walletconnect.com/ and create React project
2. Get your PROJECT_ID
3. Create .env file with content

VITE_WALLET_CONNECT_PROJECT_ID=<YOUR_PROJECT_ID_HERE>

4. Run

npm run build

5. Commit and push changes to repository to trigger GitHub pages development CI Action

PS It seems that app URL should be <your_domain>/docs/index.html and works only after npm run build
PSS Thank you very much for this repository ! It is a great starting point to learn Telegram mini app development