DOC: Update contributing.rst to give suggestions on non-code contributions
Based on a conversation at the NumFOCUS project summit.
I am not an RST expert so apologies if there are any weird mistakes here Also, this CI problems seem to be caused by your changes, if you can have a look: https://github.com/pandas-dev/pandas/actions/runs/6157790957/job/16709259450?pr=55107#step:6:65 This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. Thanks for the pull request, but it appears to have gone stale. If interested in continuing, please merge in the main branch, address any review comments and/or failing tests, and we can reopen.