add credits to the manuals

[ThomasBreuer]

resolves #1136

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.74%. Comparing base (013ffbc) to head (27660e1).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1137   +/-   ##
=======================================
  Coverage   82.73%   82.74%           
=======================================
  Files          50       50           
  Lines        3823     3824    +1     
=======================================
+ Hits         3163     3164    +1     
  Misses        660      660           

Files with missing lines	Coverage Δ
pkg/JuliaInterface/PackageInfo.g	90.35% <100.00%> (+0.08%)	⬆️