JSHint: Ignore docs/html and docs/js

The MediaWiki doxygen documentation is generated by default under
/docs/html and includes some JavaScript files.  Since we do not maintain
that output, simply ask JSHint to kindly ignore them.

Same for the static site generated by JSDuck.

Change-Id: Ief4661128992b65aa85dfaa6f48d31745fe6ff19
Merge "JSHint: Ignore docs/html and docs/js"