chore: post_command tests not working correctly & missing documentation

[marksie1988]

Description

Changed the tests for post_command, this is required as the results include exceptions in the json if it errors, this was previously reporting a success when it may fail.

I am unable to do this for renameFiles as this requires there actually be files on the test servers which we don't have at this time.

Related issues

closes #157

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• CI / Tests update
• Documentation update

How has this been tested

• I have added new tests where required
• I have run nox -s tests locally and passed
• I have tested this feature in a python script

[codecov]

Codecov Report

Merging #160 (bf3688a) into master (b56bb63) will increase coverage by 0.23%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #160      +/-   ##
==========================================
+ Coverage   93.05%   93.28%   +0.23%     
==========================================
  Files          15       15              
  Lines        1066     1073       +7     
==========================================
+ Hits          992     1001       +9     
+ Misses         74       72       -2     

Files Changed	Coverage Δ
pyarr/models/radarr.py	100.00% <ø> (ø)
pyarr/models/readarr.py	100.00% <ø> (ø)
pyarr/models/sonarr.py	100.00% <ø> (ø)
pyarr/const.py	100.00% <100.00%> (+100.00%)	⬆️
pyarr/lidarr.py	91.34% <100.00%> (+0.12%)	⬆️
pyarr/models/lidarr.py	100.00% <100.00%> (ø)
pyarr/radarr.py	97.97% <100.00%> (+0.01%)	⬆️
pyarr/sonarr.py	97.56% <100.00%> (+0.01%)	⬆️