Add P2P API Docs

[ohager]

At the moment, just the extensive HTTP Web API is documented using OAS.

For completeness it's nice having the P2P API documented in the same style (OAS).
I recommend to add a new path to serve (similar to api-doc) a p2p-doc.

[damccull]

I've done quite a bit of documentation on them at https://signumoasis.xyz/docs/api/p2p/. You should be able to get quite a bit of info to create this new interactive api doc from here.