Clarify/enhance endpoint naming rules

[tdonohue]

This is based on the discussion that took place in today's (Sept 22, 2022) DevMtg and in #181 .

Mostly, this clarifies existing rules, but also enhances our rule regarding use of abbreviations and endpoint name length.

I'm moving this to the 7.5 board as it's not required for 7.4, but early reviews are welcome.

[mwoodiupui]

Thanks, looks well to me.