Full help/usage display and modification example

[tansy]

Example of help modification as documentation supplement.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (e4ee3af) to head (0ff4e33).
Report is 40 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##              main      #975     +/-   ##
===========================================
  Coverage   100.00%   100.00%             
===========================================
  Files           17        17             
  Lines         4546      4680    +134     
  Branches         0      1005   +1005     
===========================================
+ Hits          4546      4680    +134     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[phlptp]

Thanks this looks good, I will integrate after we get the release out so it gets tested and built with all the other examples, but I think this will be helpful.

[tansy]

That 'no parameter option' was my guess, and I just noticed, that it has `level' parameter. I think that needs correction.

Shall it be
encode->add_option("-R, --remove", nullptr, "remove input file");
or
encode->add_flag("-R, --remove", "remove input file");?

Also I world add an option to make space between shirt and long option description (-h,--help -> -h, --help), but don't know how.

[phlptp]

Going to merge this, as the failures are unrelated (an update in test runners). Will clean it up soon in a subsequent PR.