its => belonging to it
it's => it is / it has

remove image description from docs

Update documentation on offset for small medium and large devices.

Remove type attribute of tag "script".

- Add new mixin to generate and customize focus state as needed
- Adds variable to set default color
- Include clear disclaimer about customizing this—it's about users', so
don't go making everything bright red and expect them not to be
confused or alarmed.

Relevant issues: #2742, #4185, #7942, #8171, #8610, #9044

Fix #7108: btn group styling

In HTML5 in tag script, the type attribute is no longer required. The default value is "text/javascript".
http://www.w3.org/TR/html5/scripting-1.html#attr-script-type

adjust description & give source for nested `.btn-group`s example

Greater standardization of sizing terminology

In class names:
* large => lg
* small => sm
* mini => xs ("Extra small")

In screen size categories:
* Tiny => Extra small

fix #9051

Change value with variables for btn-large, btn-small and pagination