Link to the rules from the readme

[bbodenmiller]

PR Summary

PR Checklist

• 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
• This PR is ready to merge and is not Work in Progress.
  • If the PR is work in progress, please add the prefix WIP: to the beginning of the title and remove the prefix when the PR is ready.

[rjmholt]

I think this is a good idea for discoverability, just want to make sure the link is in the right place. @bergmeister @JamesWTruher is there anywhere else you'd put the link in the README?