Nicer setting descriptions

[HO-COOH]

Fix

1. Make the setting descriptions to proper markdownDescription as necessary.

2. As you can see in the gif, I was confused by what values are valid, because I click on the setting and then the default array is empty. (I think it's an issue of vscode itself). So I added those valid values in the descriptions.

[codecov]

Codecov Report

Merging #209 (db8c2ad) into master (c703c6a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #209   +/-   ##
=======================================
  Coverage   93.34%   93.34%           
=======================================
  Files           5        5           
  Lines         842      842           
  Branches      240      240           
=======================================
  Hits          786      786           
  Misses         56       56           

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[cschlosser]

Thank you!