Partial readme rewrite

Remove the outdated generic installation guide and point to
platform-specific ones instead, update contact info, protocols we
support, etc.
8 jobs for refactor/readme in 9 minutes and 3 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #76399
build

00:03:45

 
  Test
passed #76403
analysis

00:04:02

passed #76402
lint

00:00:48

passed #76400
unit-testing

00:05:17

87.1%
failed #76401
unit-testing-rum

00:03:06

 
  Benchmark
skipped #76404
benchmark
 
  Deploy
skipped #76405
allowed to fail manual
review_app
skipped #76406
allowed to fail manual
stop_review_app
 
Name Stage Failure
failed
unit-testing-rum Test
Pleroma.CaptchaTest
* test Kocaptcha new and validate * test Kocaptcha new and validate (0.1ms)


Finished in 106.4 seconds
2000 tests, 2 failures, 1 skipped

Randomized with seed 954805
ERROR: Job failed: exit code 1