Update Docs with missing elements and update to latest Sphinx/Read The Docs

[RogerSelwyn]

Docs update requires an action (which is in this PR) to build the pages, then the standard GitHub pages deployment will deploy that.

Currently the action is created to run on every push to master.

The PR also includes missing key docs for components that have been added since the last publication of the docs. I noted the docs had a stub entry for Query utils, which needs rounding out. It was not in the previous usage ToC, but it creates a warning from Sphinx because the definition for it is there and the warning stated it wasn't in a ToC.

[RogerSelwyn]

@alejcas Not sure if this was of value to you. If not I'll bin it. I have some time spare, so could potentially expand on some of the documentation, but I'll only do it if it is of use.

[alejcas]

Hi @RogerSelwyn, I’m having a lot of work these days. Will check this asap

[RogerSelwyn]

@alejcas I thought it might be that, but I wanted to check. I’m happy to try an add some more descriptive documentation (perhaps extracting some from the Read Me) where it is missing rather than just the content scraped from the code. I’ll see what I can do over the coming days.