Refactor Sphinx documentation build workflow and update requirements file

[Yaswant Pradhan (yaswant)]

I've refactored the workflow slightly. Also, added sphinx-lint (this needs to be addressed first before compiling the docs)

[Yaswant Pradhan (yaswant)]

I shouldn't review this PR. Think Andrew Coughtrie (@andrewcoughtrie) can find some time to review it.

Pierre Siddall (@Pierre-siddall) as discussed, if you can update the README file to clarify the Requirements file section and add another section to to show how this action can be used alongside deploy pages action.

[Pierre Siddall (Pierre-siddall)]

I shouldn't review this PR. Think Andrew Coughtrie (@andrewcoughtrie) can find some time to review it.

Pierre Siddall (@Pierre-siddall) as discussed, if you can update the README file to clarify the Requirements file section and add another section to to show how this action can be used alongside deploy pages action.

I agree I'll switch this PR into draft mode for now while I tackle these items before they head into review from Andrew Coughtrie (@andrewcoughtrie) .

[Yaswant Pradhan (yaswant)]

I think it would be ideal to set a default timeout-minutes

timeout:
  description: "Timeout minutes for the job"
  default: 5  # or maybe 10
  type: number
  required: false

[Pierre Siddall (Pierre-siddall)]

After discussion between Yaswant Pradhan (@yaswant) and I this looks like it's ready to be reviewed. Over to Andrew Coughtrie (@andrewcoughtrie) for CR.

[Yaswant Pradhan (yaswant)]

Andrew Coughtrie (@andrewcoughtrie) - do you have some time to review this quickly please?

[Andrew Coughtrie (andrewcoughtrie)]

Looks good, some suggested changes to the README.md.

[Andrew Coughtrie (andrewcoughtrie)]

This all looks good to me now.