Cleanup haddocks

* Fixes typos,
* Adds missing periods
* Consistently uses 'Elm' rather than 'elm'
* Surrounds `deriveElmJS` in single quotes so it hyperlinks to the function from Haddocks + is showed in a monospace font.
Make LANGUAGE pragma casing consistent in docs
Merge pull request #1 from MaxGabriel/patch-1

Cleanup haddocks