Remove GHA docs build
This PR removes the redundant GHA docs workflow, this is done by readthedocs now.
Maintenance will be performed on git.ligo.org, containers.ligo.org, and docs.ligo.org on Tuesday 2 July 2024 starting at approximately 9:30am PDT. It is expected to take around two hours and there will be several periods of downtime throughout the maintenance. Please address any comments, concerns, or questions to the helpdesk.
This PR removes the redundant GHA docs workflow, this is done by readthedocs now.