Add API Documentation

[jacksturt]

Add documentation for this api: https://web-api.pyth.network/

Not sure if this exists and I can't find it, or if this is meant to be closed to the public. I am looking to be able to get the pythnet feed ID given a market name. For example, and endpoint like https://web-api.pyth.network/market?symbol=CRYPTO.SOL/USDC which will return info including the public key 'H6ARHf6YXhGYeQfUzQNGk6rDNnLBQKrenN712K4AQJEG'