DOC: Add v0.22 whats new page

[greglucas]

This adds the initial what's new page for the v0.22 release. Let me know if I missed any other features that should be called out, or deprecations/removals that we should discuss.

I've put a date placeholder for now and will update that once the release builds PR gets merged and we decide when to make a release.

Two topics for discussion:

1. Thoughts on a date for release? I'd vote for next week sometime to try and get the updates out to work with Scipy and hopefully get out ahead of the Matplotlib 3.8 release.
2. Where to put the docs when we deploy? Stick with where we have been putting them https://github.com/SciTools/scitools.org.uk, or move to RTD or GitHub Pages: Move the documentation to ReadTheDocs? #1765

[dopplershift]

IMO, the sooner the better.

We should also probably move the items from the 0.21.2 milestone to 0.22?

[greglucas]

I just added a release date of Thursday, August 3. (2 days from now)

I think this is the only PR we need to get in. But, let me know if I missed any others that should make it in before release.

[dopplershift]

@bjlittle Can you remove AppVeyor from the Cartopy repo? I tried to do it but because we're the last "user", it needs to remove it from the entire organization, which needs an org owner to do.

[trexfeathers]

@bjlittle Can you remove AppVeyor from the Cartopy repo? I tried to do it but because we're the last "user", it needs to remove it from the entire organization, which needs an org owner to do.

I have 'suspended its access'. Will uninstall it if someone else from @SciTools/admins can tell me that's OK.

[trexfeathers]

@bjlittle Can you remove AppVeyor from the Cartopy repo? I tried to do it but because we're the last "user", it needs to remove it from the entire organization, which needs an org owner to do.

I have 'suspended its access'. Will uninstall it if someone else from @SciTools/admins can tell me that's OK.

So I assume the ❌ will go away if the CI is respun? Don't want to tread on any toes.

[dopplershift]

@trexfeathers Thanks. Looks like the status for this PR is the status from AppVeyor. We'll have to keep an eye out on a future PR.

[dopplershift]

Looks good to me. Happy to see this release get out the door. If we need a bugfix, hopefully that's easier now with everything else we (you, @greglucas) set up. 🎉

[trexfeathers]

@bjlittle Can you remove AppVeyor from the Cartopy repo? I tried to do it but because we're the last "user", it needs to remove it from the entire organization, which needs an org owner to do.

I have 'suspended its access'. Will uninstall it if someone else from @SciTools/admins can tell me that's OK.

Have now uninstalled, with approval from @bjlittle

[QuLogic]

Indented too much; it'll cause a blockquote. Should be aligned with the wrapped text's indent:

Suggested change

	.. plot::
	.. plot::

[greglucas]

Good catch, thanks!