Replace plugin stub descriptions with actual descriptions.

[siakaramalegos]

Connects #5073

Replaces all stubbed plugin descriptions with real ones so that the search page will show real descriptions:

I'm having trouble getting the local www folder/project running in development, so this PR still needs verification.

[siakaramalegos]

Fixed grammar here, fyi.

[siakaramalegos]

See #5073 (comment) - In this PR I'm assuming Algolia's React InstantSearch is using the core /packages/ folder as it's data source, but I cannot verify. Someone on the team that has access to the React InstantSearch set up will need to verify. The dev version does not point directly to the local /packages/ folder.

[DSchau]

Looks great; thanks!

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