Missing documentation for on `BootstrapNavbarHelper`

[curtisgibby]

I had to dig around a bit in your issues history to find your example of using the navbar helper. It would be useful to have this information on the main documentation page.

[Holt59]

I am working on a new documentation written in Markdown and using mkdocs to generate the HTML. Feel free to contribute: https://github.com/Holt59/cakephp3-bootstrap-helpers/tree/mkdocs

[Holt59]

New documentation is now live with the Navbar example:

https://holt59.github.io/cakephp3-bootstrap-helpers/navbar-helper/basics/