#24373 : Documentation/Navbar : Refer to utility classes used. Hidden when printing...

#24373 : Documentation/Navbar : Refer to utility classes used. Hidden when printing.  (#24380)

* Refer to utility classes uses. Add Printing section

refer to (not navbar) classes used for newbies
navbars don't print, so add example of a print-only alternative

* typos, add links

typo in {% example %}
add links to component pages

* grammar

* Add a dropdown with divider to the main example

* change id name to stop travis error

I assume id="camelCase" is the standard for id names, rather than the clearly superior id="underscore_words"

* review changes

still like to emphasise the foreign utility classes in the main example
bg-light's name is self explanatory (so its obvious where to look it up), but mr-sm-2's name isn't at first

* review changes

* grammar

* .fixed-top/bottom don't reserve space on the screen

... as they are position:fixed.
better wording welcome

* copyediting

- rewrite utils line and link to the utils pages
- restore the paragraphs to the placement section
- fix formatting and grammar