docs: update docstrings for httping, indirecting, keeping, notifying, oobiing

[alecforston]

Update the docstrings for:

• httping.py
• indirecting.py
• keeping.py
• notifying.py
• oobiing.py

Code change:

Restored the following code to keri.indirecting.HttpEnd.on_post:

        if req.method == "OPTIONS":
            rep.status = falcon.HTTP_200
            return

        rep.set_header('Cache-Control', "no-cache")
        rep.set_header('connection', "close")

        cr = parseCesrHttpRequest(req=req)

This code block likely got deleted by a previously-merged PR.