Build and deploy to latest once a week, running at the start of the week

[oraNod]

Follows on from #2047

The workflow to build the package docs should run once a week and deploy the devel branch of this repository to the branch of the package-doc-builds that corresponds to the current latest version. At the moment that branch is 10 but will change to 11 shortly after core release 2.18.

[ansible-documentation-bot]

Thanks for your contribution, @oraNod! Please make sure that your issue includes sufficient and meaningful details in the description.
Issue descriptions are important so others can fully understand and reproduce the issue.

[x1101]

After discussion in the most recent DaWGs meeting, I'm going to take a look at this. Please assign to me