Docs/restructure readme

[seyfeb]

Topic and Scope

Restructure the README file

• Rearrange sections
• Move clients to separate file
• Fix missing CI badge

Concerns/issues

None

Formal requirements

There are some formal requirements that should be satisfied. Please mark those by checking the corresponding box.

• I did check that the app can still be opened and does not throw any browser logs
• I created tests for newly added PHP code (check this if no PHP changes were made)
• I updated the OpenAPI specs and added an entry to the API changelog (check if API was not modified)
• I notified the matrix channel if I introduced an API change

[github-actions]

Test Results

     12 files     572 suites   1m 30s ⏱️
   552 tests    552 ✔️ 0 💤 0 ❌
2 208 runs  2 207 ✔️ 1 💤 0 ❌

Results for commit 48f5d50.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

Merging #1989 (48f5d50) into master (feb842f) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1989   +/-   ##
=======================================
  Coverage   80.07%   80.07%           
=======================================
  Files          92       92           
  Lines        2650     2650           
=======================================
  Hits         2122     2122           
  Misses        528      528           

Flag	Coverage Δ
integration	21.43% <ø> (ø)
migration	5.69% <ø> (ø)
unittests	57.09% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

[christianlupus]

Lgtm