Add `disable` state to generated policy documentation

[duckpuppy]

Description

This PR adds support for documenting disabled rules to the generated policy documentation.

Testing Done

New unit tests, local testing using the example repos included in this project. A new disabled rule was added to both example sets.

Contributor License Agreement

Required for external contributors.

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• The contribution included in this request (and any subsequent revisions or versions of it) is being made under the same license as the manheim-c7n-tools project (Apache v2).
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[codecov-commenter]

Codecov Report

Merging #52 into master will increase coverage by 0.12%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #52      +/-   ##
==========================================
+ Coverage   57.61%   57.73%   +0.12%     
==========================================
  Files           8        8              
  Lines        1385     1389       +4     
  Branches      261      262       +1     
==========================================
+ Hits          798      802       +4     
  Misses        586      586              
  Partials        1        1              

Impacted Files	Coverage Δ
manheim_c7n_tools/policygen.py	99.75% <100.00%> (+<0.01%)	:arrow_up:
manheim_c7n_tools/version.py	100.00% <100.00%> (ø)

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