Make it clear how to install the plugin

[jwbth]

The markup in README.md is misleading, as it puts several alternatives into one block of code while not making it clear where the alternatives begin and end, forcing the reader to think hard about it. The pull request splits the block of code into three isolated ones, preceding each one with a comment and organizing them in a list.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.60%. Comparing base (c0ac54b) to head (ab88f4d).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2993      +/-   ##
==========================================
- Coverage   95.66%   95.60%   -0.07%     
==========================================
  Files          78       78              
  Lines        3275     3275              
  Branches     1150     1150              
==========================================
- Hits         3133     3131       -2     
- Misses        142      144       +2     

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.