this is the opposite of `.text-nowrap`, and a forces elements to wrap onto new lines.
One use case for this is extra long button text. Bootstrap buttons by default do no wrap, so this class could be used to override that behavior.
* add 'lighter' and 'bolder' font weight classes
these are 2 special values for font weight, that will give their content a font-weight value of 100 more or less than their inherited font-weight.
probably doesn't fully fulfill this issue, https://github.com/twbs/bootstrap/issues/23969, but it's a start
* Update .stylelintrc
* add 'lighter' and 'bolder' variables per @mdo 's request.
* Remove comment that duplicated some code
* Use transition mixin whenever possible
* Create a new function to reduce duplication
* Use the new `breakpoint-infix` method
* Clean up some utilities
- Align CSS properties
- In `_spacing.scss`, we had a comment saying what 'a' was for, but we removed that so this comment no longer applies
* Remove '-xs' from `.navbar-toggleable-xs` and remove duplication
* Fix outdated classes to use newer ones
- Rather than mix multiple properties in our color utilities, this splits all color and all background utils into separate classes.
- Adds new .text-white class to help lighten text color for darker backgrounds
