add mean/std to timeit decorator

[PythonFZ]

• Update documentation
• update docstrings
• write tests

[codecov]

Codecov Report

Merging #284 (75ad59c) into main (fb20d34) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #284   +/-   ##
=======================================
  Coverage   71.27%   71.27%           
=======================================
  Files          27       27           
  Lines        1194     1194           
  Branches      238      238           
=======================================
  Hits          851      851           
  Misses        317      317           
  Partials       26       26           

Flag	Coverage Δ
unittests	71.27% <ø> (ø)

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