Converting some of the rst documentation to markdown.  Attempted to
preserve whitespace and line breaks to minimize cosmetic change.

Signed-off-by: Benjamin Saunders <ben.e.saunders@gmail.com>

Improved federation configuration docs.  Specifically detailing  .well-known and SRV based delegation methods. 

Inspiration Valentin Lab <valentin.lab@kalysto.org> for https://github.com/matrix-org/synapse/pull/4781

* add trivial clarification about jemalloc

* switch from google.com to recaptcha.net

because https://developers.google.com/recaptcha/docs/faq#can-i-use-recaptcha-globally

Lots of updates to the README/INSTALL.md.

Fixes #4601.

Factor out the reverse proxy info to a separate file, add some more info on
reverse-proxying the federation port.

The readme was getting pretty unmanageable and hard to grok. This is an attempt to simplify things by moving installation instructions from the README to a separate file. I've tried to resist the temptation to fix too much stuff while I'm here - it mostly just copies-and-pastes from one doc to the other, and changes from rst to md syntax.

Co-Authored-By: anoadragon453 <1342360+anoadragon453@users.noreply.github.com>

Co-Authored-By: anoadragon453 <1342360+anoadragon453@users.noreply.github.com>

* update debian installation instructions

* docs PR is docs

* remove dh_params and set better cipher string

* Update README to not lie about required restart

Signed-off-by: Aaron Raimist <aaron@raim.ist>

* Add changelog

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Make the dependencies more like a standard Python project and hook up the optional dependencies to setuptools (#4298)

This is based on the work done by @krombel in #2601.

https://github.com/vector-im/vector-web/issues/1977 --> https://github.com/vector-im/riot-web/issues/1977
And mention of Vector as a client replaced with Riot.

Signed-off-by: Ashe Connor <ashe@kivikakk.ee>