Example client flow for PSS

[PaulLeCam]

@dleonard00 here is a first stab at describing a flow the client can implement to provide communication between 2 peers using PSS, please don't hesitate to alter anything you see fit.

I don't know about Sphinx and the usual practices for these docs, but one thing that could be useful would be to add HTML anchors to each API method in the PSS docs, so they could be linked to directly in this example or other docs.
I also noticed that there are 2 APIs documented in PSS that seem at odds with the rest: pss.GetSymmetricAddressHint(topic, symkeyid) and pss.GetAsymmetricAddressHint(topic, publickey) have an uppercase leading G while all other APIs start with a lowercase character, I think it's a leftover from the Go API.