Docs audit prompted by #13697.
[skip sauce]

The validator doesn't choke anymore on this and even though it's not spec compliant, it's needed for some IE versions. So until we move favicon.ico in root, this should do the job.

Closes #13379.

Also, use Google's CDN per #11369.

As per the docs:
http://getbootstrap.com/components/#navbar-default

  modified:   examples/carousel/index.html
  modified:   examples/jumbotron/index.html
  modified:   examples/navbar-fixed-top/index.html
  modified:   examples/navbar-static-top/index.html
  modified:   examples/navbar/index.html
  modified:   examples/non-responsive/index.html
  modified:   examples/starter-template/index.html
  modified:   examples/sticky-footer-navbar/index.html
  modified:   examples/theme/index.html

- works when viewing page via file://
- sets a good example security-wise

...because we don't support it and it may cause problems for people
trying to view the docs in IE.

Missed the <a class="btw" in my regex search

* sticky footer side scrolling
* static and fixed navbar more similar
* min-height on static and fixed navbar examples to illustrate
differences

last two items fix #9702

Changed nav-header to dropdown-header in navbar navbar-fixed-top and navbar-static-top as mentioned in Docs