[Documentation search] Update the search in order to handle different versions and languages.

Original issue submitted by @s-pace in https://github.com/babel/babel/issues/8587

👋 team,

I am working on [DocSearch](https://community.algolia.com/docsearch/) , an algolia tool. We are proud to feature the search from your documentation website.

Congrats for the v7 👏

It needed [an update from our side](https://github.com/algolia/docsearch-configs/commit/6563a0730d9a51ff3a3c0b44f7ed0ecb1d7952eb) in order to avoid having duplicates from v7 and the latest 6.26.3. No worries, everything is proactively updated (we monitor big changes)

If you want, we do offer filtering over `language` and `version`. Since you are using Docusaurus, the `version` and `language` filters are handled automatically from the Search-UI. We will need you to enable it and check that your Docusaurus instance is updated.

Please ping me if you want to enable this feature. I will PR the required changes from [your DocSearch configuration](https://github.com/algolia/docsearch-configs/blob/master/configs/babeljs.json).

Your website will have an adaptive search instead of only retrieving the latest version.

Start by reviewing the Babel DocSearch configuration at algolia/docsearch-configs/configs/babeljs.json and checking whether the Docusaurus instance is updated. Done means the documentation search supports filtering by language and version without duplicating results across versions.

Written by the indexing model from the issue text.