Fixes #1720 - move rule docs and update tests

[sdwheeler]

PR Summary

PR Checklist

• Moved ./RulesDocumentation to ./docs/Rules

• Moved ./docs/markdown to ./docs/Cmdlets

• Update Pester test for documentation

• PR has a meaningful title

  • Use the present tense and imperative mood when describing your changes

• Summarized changes

• Change is not breaking

• Make sure all .cs, .ps1 and .psm1 files have the correct copyright header

• Make sure you've added a new test if existing tests do not effectively test the code changed and/or updated documentation

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[rjmholt]

Looks like platyPS invocations in the build script also need to be updated

[sdwheeler]

@rjmholt OK, I missed that. Will update.

[sdwheeler]

@rjmholt Fixed the build script.

[andyleejordan]

Hi, @rjmholt and @sdwheeler this PR caused a regression in the VS Code extension because the URL used to find the documentation was changed. Heads up to coordinate changes like this in the future. I'm pushing a new release today with the bug-fix.