Guide: How to use other tokens in the market

[jamiehewitt15]

Many people intend to use their own token or something ubiquitous (like USDC) when starting their own market. As part of the "Build a marketplace" series of guides we can add a tutorial on how to add to alter the list of tokens that can be used. We should wait at least until https://github.com/oceanprotocol/market/pull/1516 is merged.