Improve diagnostics strings

[christophfroehlich]

I was working with diagnostics a bit, and found the error messages and descriptions a bit confusing. Maybe this enhances it a bit?

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 89.55%. Comparing base (4f0f300) to head (869dad3).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
controller_manager/src/controller_manager.cpp	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2078      +/-   ##
==========================================
+ Coverage   89.53%   89.55%   +0.01%     
==========================================
  Files         139      139              
  Lines       15124    15125       +1     
  Branches     1283     1283              
==========================================
+ Hits        13542    13545       +3     
- Misses       1095     1096       +1     
+ Partials      487      484       -3     

Flag	Coverage Δ
unittests	89.55% <0.00%> (+0.01%)	⬆️

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

Files with missing lines	Coverage Δ
controller_manager/src/controller_manager.cpp	76.40% <0.00%> (+0.08%)	⬆️

... and 1 file with indirect coverage changes

[saikishor]

What do you think about this?. If you are still fine with original text, let's go for it ;)

The other changes LGTM

[saikishor]

Thanks for the follow-up

[bmagyar]

Thank you!