Regenerate flytectl docs

[neverett]

Why are the changes needed?

Not a high priority, but while working on flyte docs overhaul stuff, I noticed the flytectl docs were quite stale, so I regenerated them.

What changes were proposed in this pull request?

Updated flytectl docs, plus requirements files for running the regeneration script, which invokes Sphinx.

How was this patch tested?

Tested locally.

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

N/A

Docs link

https://flyte--5914.org.readthedocs.build/en/5914/api/flytectl/docs_index.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.82%. Comparing base (8bd573e) to head (ab160f7).
Report is 6 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #5914       +/-   ##
===========================================
+ Coverage   18.30%   36.82%   +18.52%     
===========================================
  Files         380     1309      +929     
  Lines       53948   130938    +76990     
===========================================
+ Hits         9873    48217    +38344     
- Misses      43238    78537    +35299     
- Partials      837     4184     +3347     

Flag	Coverage Δ
unittests-datacatalog	51.58% <ø> (ø)
unittests-flyteadmin	54.03% <ø> (?)
unittests-flytecopilot	11.73% <ø> (ø)
unittests-flytectl	62.40% <ø> (ø)
unittests-flyteidl	6.92% <ø> (ø)
unittests-flyteplugins	53.64% <ø> (?)
unittests-flytepropeller	43.00% <ø> (?)
unittests-flytestdlib	55.41% <ø> (?)

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