Update README doc for INFURA_ID

Author: kavimaluskam

frontend/README.md

@@ -85,6 +85,7 @@ nvm install; # to install the version in .nvmrc
 3. Start the development server with `yarn dev`
 4. Open development site by going to `http:localhost:3000`
 5. To test Walletconnect functionality, copy `.env.development` to `.env.local` and fill in your `INFURA_ID`.
+   `INFURA_ID` can be easily obtained by register at <https://infura.io/>, then create a new Ethereum project for free.
 
 ## Contributing