Add all the current wiki sources (currently has like 20 wikis). Make that searchable.

[xabriel]

@tchin25 took care of adding all wikis by opening and parsing a publicly available list: https://github.com/xabriel/listen-to-wikipedia/blob/7fc6c857681c749e964be2b580557598bf066d16/src/composition.js#L4-L27

He made it searchable on this commit: https://github.com/xabriel/listen-to-wikipedia/commit/2ba282b95371c9b3909ae8c6c33dde717db08d7b