add section for websocket event listener (#5619)

### Description

a small section explaining how to set up a smart contract event listener using web3js and forno

packages/docs/developer-resources/forno/README.md

@@ -24,3 +24,7 @@ Baklava = 'https://baklava-forno.celo-testnet.org'
 
 Mainnet = 'https://forno.celo.org' or 'wss://forno.celo.org/ws' (for websocket support)
 ```
+
+### Websocket connections & Event listeners
+
+Websocket connections are useful for listening to logs (aka events) emitted by a smart contract, but Forno only allows a websocket connection for 20 minutes before disconnecting. On disconnect, you can reconnect to the websocket endpoint to keep listening. [Here](https://gist.github.com/critesjosh/a230e7b2eb54c8d330ca57db1f6239db) is an example script of how to set up an event listener that reconnects when the connection is broken.