Collapsible Naming Conventions Inconsistent

[willpracht]

Looking at the new markup for Collapsibles (formerly Accordions), there's a minor inconsistency in naming:

<a class="accordion-toggle"...

Maybe this should be changed to "collapsible-toggle" for consistency. The id's used in the documentation should probably also be updated to be #collapsible1, etc.

[mofamtech]

I'm new to Bootstrap, so maybe I am missing something, but I don't see the .accordion-toggle class in the distribution bootstrap.css. I've wondered about this as it appears in the example code.

[ggam]

In fact, it seems that class isn't really needed as the example still works after removing it. I'll do a pull request for that.