Add correct links to the Emacs integration of tern-lint

[mykhas]

Hi!

Apparently, @katspaugh has moved his tern-lint.el from repository to gist, so link to it should be fixed.

Unfortunately, that version of the extension doesn't work with Emacs 26.1 and latest flycheck, so I've create new version of test-lint.el and published it as one more gist. Would it be ok to add link to it to the Docs section?

Best,
Mykhas.