Proposed change to disabled link state docs

Created by: necolas

The current nav docs say:

For any nav component (tabs, pills, or list), add .disabled for gray links and no hover effects. Links will remain clickable, however, unless custom javascript is implemented to prevent those clicks.

You could instead recommend that people remove the href attribute when using the disabled class, as that's what the HTML5 spec recommends for "placeholder" links. That way, there's no need to use JS and your document semantics are improved in the process.