Add new template, Cover
Fixes #11829: Adds .make-xs-column mixins
Merge branch 'master' of github.com:twbs/bootstrap
Change variable
Merge branch 'master' into cover_template
Restyle the blockquote to not thin text or change line-height
finalize blog template
Fixes #11805 with docs mention of navbar
update tooltip docs
Fixes #11833: add warning to docs for popover multiple line positioning; update it's docs with example markup, too
Browser/device support docs update

* Fixes #11055: add mention of select menu styling on Android stock
browsers with included optional fix
* Update IDs and docs nav to include bookmark links to each section
* Add callout to navbar docs about fixed position, inputs, and virtual
keyboard
Fixes #11770: Move component-animations.less to the utility section of import list to match Customizer
Fixes #11799: Mention support of number of add-ons in docs