Implemented COMMAND DOCS by always throwing NotImplementedError

[dvora-h]

Pull Request check-list

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• Does $ tox pass with this change (including linting)?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
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Description of change

closes #1946

[codecov-commenter]

Codecov Report

Merging #2020 (d323b92) into master (a77df17) will decrease coverage by 0.39%.
The diff coverage is 52.23%.

@@            Coverage Diff             @@
##           master    #2020      +/-   ##
==========================================
- Coverage   92.60%   92.20%   -0.40%     
==========================================
  Files         100      100              
  Lines       20912    20984      +72     
==========================================
- Hits        19365    19349      -16     
- Misses       1547     1635      +88     

Impacted Files	Coverage Δ
tests/test_function.py	25.30% <20.31%> (-74.70%)	⬇️
redis/cluster.py	91.93% <61.53%> (-0.51%)	⬇️
redis/commands/core.py	85.95% <75.00%> (-1.28%)	⬇️
redis/commands/json/__init__.py	97.56% <75.00%> (-2.44%)	⬇️
redis/commands/parser.py	88.40% <75.00%> (-1.92%)	⬇️
redis/commands/timeseries/__init__.py	94.73% <80.00%> (-5.27%)	⬇️
tests/test_commands.py	99.20% <90.90%> (-0.07%)	⬇️
redis/commands/cluster.py	94.87% <100.00%> (+0.04%)	⬆️
tests/test_bloom.py	99.54% <100.00%> (+<0.01%)	⬆️
tests/test_graph.py	90.62% <100.00%> (+0.06%)	⬆️
... and 8 more

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