Add missing documentation

[laurenyu]

Merge Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your pull request.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have updated the changelog with a description of my changes (if appropriate)
• I have updated any necessary documentation (if appropriate)

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[codecov-io]

Codecov Report

Merging #575 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #575   +/-   ##
=======================================
  Coverage   92.78%   92.78%           
=======================================
  Files          71       71           
  Lines        5366     5366           
=======================================
  Hits         4979     4979           
  Misses        387      387

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[eslesar-aws]

There is already a randomcutforest.rst file in the doc folder...the file added here has no extension.

[laurenyu]

@eslesar-aws ah, so I was wrong in #576. removed the file i added