2.9 release of the userguide

[IAlibay]

In lock-step with the core library, we can now do a 2.9 release of the userguide once #414 is merged.

[orbeckst]

I merged PR #414

[orbeckst]

Is the UG release still following the documented steps https://userguide.mdanalysis.org/stable/preparing_releases_and_hotfixes.html#create-a-release-of-the-userguide ?

[orbeckst]

Do we want to wait for PR #404 and #406 ?

[lilyminium]

@orbeckst -- yes, that's still the process. Let's wait for #404

[orbeckst]

The other PRs #404 and #406 have been merged. We can do a release of the UG.

[orbeckst]

@lilyminium or @marinegor , would one of you be able to do the UG release? (Sorry, I also do GSOC at the moment so can't put this on my plate.)

[RMeli]

I should have some time tonight, I can take this on. But if it is not released by tomorrow and some of you have time, then please go ahead.

[RMeli]

Snapshots and release notes are already up to date. I'm going to do the release now.

[RMeli]

🤞

[RMeli]

Looks like this time I've been lucky: https://userguide.mdanalysis.org/2.9.0/

[orbeckst]

Fantastic, thank you!!