CI: Add a workflow to automatically create an issue on the docs repo from a PR in this repo

[prrao87]

This is a workflow enhancement suggestion to help us write and maintain better docs.

Whenever someone issues a PR to add a new feature that requires documentation, they can mark it with the label "needs-documentation". Then the CI bot would kick in and create a new issue on our docs repo, where it links back to the PR in this repo that adds the feature. This will help on two counts:

• We can link the docs issue directly back to the feature PR that implemented it (or the issue that was flagged) on our main repo
• We can reduce the chances of forgetting to document new features

See this workflow on the DuckD repo as an example. I think having a workflow like this would work great for our purposes, too!