Initial commit of python-recommonmark

Summary: Starting with version 0.6.0. Required for LLVM man pages.

Test Plan: Use to render LLVM man pages

Reviewers: Triage Team, JoshStrobl

Reviewed By: Triage Team, JoshStrobl

Subscribers: JoshStrobl

Differential Revision: https://dev.getsol.us/D9682