chore(deps): update docusaurus to rc.1

[pepopowitz]

This PR brings the docusaurus dependencies fully up to date, with version rc.1!

Regression (maybe?): whitespace below footer

Update 2: The regression isn't visible on staging, so I think this was a weird fluke temporary thing.

Update: I'm not able to reproduce the whitespace regression anymore. I don't know what was going on before, or what's going on now that it's fixed. Once this is merged I'll peek at staging to see what it looks like, and decide what to do if it includes the regression.

Out-of-date details about this whitespace regression

One small visual regression is introduced in this PR -- there is now always white space below the footer, on every page:

I'd noticed this issue on some pages prior to this update, especially ones with long content, but now it seems to be everywhere.

I'm not sure which change in the changelogs (https://docusaurus.io/changelog/2.0.0-beta.21, https://docusaurus.io/changelog/2.0.0-beta.22, https://docusaurus.io/changelog/2.0.0-rc.1) introduced this issue.

My plan is to take an hour to try to figure this out as part of this PR. If I can't figure it out in that amount of time, I leave it up to reviewers to tell me if this is an acceptable regression or if I need to dig further. Please, leave your opinion in the comments if you'd like! My personal feeling is that if it's easy to figure out, great, otherwise treat it as non-blocking and create an issue to investigate as a follow-up.

No other changes

Aside from that regression, there are no new console errors, unsatisfactory UI changes, or apparent loss of functionality introduced by this update.

Proof it still looks the same

Proof of no errors in the console

[akeller]

I'd noticed this issue on some pages prior to this update, especially ones with long content, but now it seems to be everywhere.

The behavior was inconsistent, so it's a bummer to see the consistency went the wrong way...

I had a look at open issues for Docusaurus and didn't see anything relevant. I 100% support timeboxing this to 1hr and don't see it as a blocking change. Sure it's annoying, but it's not hurting anything. Always progress 😄

[pepopowitz]

I updated the body of this PR to reflect it, but summarizing here --

I'm not able to reproduce the whitespace regression anymore. 🤷 It just stopped happening locally. I'm going to merge this as-is, and if staging looks bad we can re-evaluate whether (and when) this regression needs to be fixed.

[pepopowitz]

For posterity -- I don't see the regression in staging, so I am not planning to track any work for it.