Enable versioned readthedocs documentation for each tag

[manics]

trafficstars

Proposed change

JupyterHub has readthedocs for all releases, which means you can link to a particular page in a particular version. This is useful when permanent links are wanted.

Z2JH only seems to has readthedocs for each branch(?):

Can we publish Z2JH docs for each tag?

Alternative options

Do nothing

Who would use this feature?

Anyone wanting to reference the docs for a particular version of Z2JH.

(Optional): Suggest a solution

I've taken a quick look at the readthedocs settings but it's not obvious where this is configured. I can do some digging if we're happy to go ahead with this.

[manics]

@consideRatio What do you think of this? It'll make linking to documentation on Discourse a lot easier, since it ensures in-page hyperlinks won't break if the documentation is refactored.

[manics]

There's also a problem on latest. The current stable RTD docs has a version selector in the bottom right (using Firefox on a desktop):

This is missing on latest

Note the latter problem may be intermittent- if you start with the stable docs and then go to latest sometimes the selector appears, but disappears after a refresh (a caching issue?).