Add Web3img list of public gateways (#1637)

Co-authored-by: ElPaisano <[email protected]>

Author: HelloWeb3IMG

docs/concepts/ipfs-gateway.md

@@ -72,6 +72,8 @@ Public gateway operators include:
 
 Protocol Labs maintains a [list of public gateways](https://ipfs.github.io/public-gateway-checker/) and their status.
 
+[Web3IMG](https://web3img.com) also maintains an unofficial [list of public gateways](https://bestipfs.net). Please do your research before using any third-party gateways or websites.
+
 ## Gateway types
 
 :::warning
@@ -97,7 +99,7 @@ Configuring a reverse proxy is the most popular way for providers handling authe
 
 ![Auth with Reverse proxy](./images/ipfs-gateways/public-authed-gateway.png)
 
-Providers can design their own centralized authentication service like [Infura IPFS Auth](https://infura.io/docs/ipfs#section/Authentication/Overview), or a decentralized authentication service like [IPFS W3Auth](https://wiki.crust.network/docs/en/buildIPFSWeb3AuthGW)).
+Providers can design their own centralized authentication service like [Infura IPFS Auth](https://docs.infura.io/networks/ipfs/how-to/authenticate-requests), or a decentralized authentication service like [IPFS W3Auth](https://wiki.crust.network/docs/en/buildIPFSWeb3AuthGW)).
 
 ### Resolution style