Add redirect for version doc change in block editor handbook

[mkaz]

The block api versions document was renamed in ​https://github.com/WordPress/gutenberg/pull/30980 from versions.md to block-api-versions.md to be consistent with the rest of the file names

We need add a redirect for:

'reference-guides/block-api/versions/' => 'reference-guides/block-api/block-api-versions/',

[coffee2code]

@mkaz: When do you anticipate the changes to Gutenberg docs being committed? If we commit the fix for this ticket now before that PR gets merged, it'll redirect to nothing until that merge.

Ideally we get this in as soon after the merge as possible, which I've got the commit ready to go to do so.

[mkaz]

@coffee2code, I expect to do it tomorrow morning for me (Pacific Time)
I'm waiting on Justin to offer any comments on the PR before merging.

If you want I can DM you in Slack after I merge it?

[coffee2code]

@mkaz: Sounds good. I'm PT too, so anytime before 1pm would be great.

[mkaz]

PR is merged ​https://github.com/WordPress/gutenberg/pull/30980
So this change can get comitted.

Thanks for the assist!

[coffee2code]

In 10919:

Developer, Block Editor Handbook: Add redirect for renamed imported Block API Versions page.

Props mkaz.
Fixes #5710.