Switch from push to pull for updating man pages

Currently there is the [update-docs](https://github.com/GothenburgBitFactory/timewarrior/blob/develop/.github/workflows/update-docs.yml) GitHub action in the Timewarrior repository, which pushes the current man pages to the Timewarrior site repository on a new release.

This should be changed to an action in this repository, pulling the man pages from the Timewarrior repository instead. This action could still be triggered by a release event.

Start with .github/workflows/update-docs.yml and inspect how it is triggered by a release and currently pushes man pages to the site repository. Done means an action in this repository pulls the man pages from the Timewarrior repository when a release occurs, replacing the existing push flow.

Written by the indexing model from the issue text.