Support for Ansible 9 docs

[samccann]

So today, the version switcher only has two options- latest, and devel.

But with the decision to have Ansible 9 around for longer, we have two options:

• Continue to have only latest/devel in the version switcher, but publish updates to Ansible 9 docs at the direct url (aka docs.ansible.com/ansible/9/).
• Add Ansible 9 to the version switcher and maintain that for the length of the release.

[samccann]

First option is easy peasy. The second option involves getting into the version switcher. I 'think' it's fairly easy as well, but before we do that, wanted to see what folks think. @gotmax23 as the main proponent for the longer release cycle of Ansible 9, what are your thoughts?

[samccann]

Related to #1250

[felixfontein]

I'm for having 9 in the version switcher :)

[oraNod]

Throwing this out here but the migration to readthedocs will allow us to get rid of the custom version switcher. RTD provide a builtin version switcher with the widget which makes our custom one a bit redundant. I've been told was kind of hacked together anyway. It probably doesn't make much difference to this issue but might be worth consideration.

[gotmax23]

I also think 9 should be a standalone item in the version switcher.

[samccann]

Discussed in DaWGS:
1 - Yes, we will need to continue publishing Ansible 9 docs for the duration.
2 - Yes, we should include 9 in the versin switcher.