Deprecate the Docusaurus config

[slorber]

We now have an internal TS config versioned alongside the rest of the packages: facebook/docusaurus#9050

As discussed previously here, we'd like to deprecate the Docusaurus base config of this repo. Not sure how to do so though 😅

[orta]

Makes sense, we can add support for deprecating at npm level to this repo - but there's no (safe) way to deprecate from the typescript side. Or I can do it manually at some point.

(The unsafe way is to break the build intentionally, but that's a bit rude)

[slorber]

The thing is, Docusaurus v2 users should still use this so not sure what to do.

Not sure it would be good to deprecate all versions of this package on npm 😅

But maybe you could publish this package as a v2.0 that breaks the build? 🤷‍♂️