feat: update docs for new query server config

[janl]

See apache/couchdb#1602

[wohali]

Think this needs updating for changes to SSL config still. We fully scrubbed out proxy stuff and os_daemons already.

Don't think we need to document configuring the http global handlers, but if you want, go for it.

[flimzy]

I know you didn't change this, but "different" should be "differently", and "like" seems very informal, IMO.

Suggested change

	language, but you have to name them different (like `PYTHONDEV` etc.).
	language, but you have to name them differently (i.e. `PYTHON` and `PYTHONDEV`).

[wohali]

@janl please don't forget about this one, needs to land before 2.3.0 can go out the door. thanks!

[wohali]

@janl since I merged the release notes already, and it includes everything for this PR, just drop your version of src/whatsnew/2.3.rst and src/whatsnew/index.rst and we should be fine.

[janl]

@wohali can you take this over from me?

[wohali]

@janl ok

[wohali]

@flimzy can I get a final review here? I've rewritten a bunch of the...problematic text surrounding these changes to be more up to date (for instance, replacing "SSL config" with "HTTPS config", which I think more people will understand.)

[flimzy]

Only one minor change.

[wohali]

@flimzy Good catch, fixed! Will consider that a +1 and merge momentarily.

Thanks again for doing the bulk of the work here @janl !