Fixed crazy-making typo on home page

...at least if you're a writing nerd :P "Bootstrap ships with vanilla CSS, but *its* source code..."
Merge pull request #13946 from rufo/patch-1

Fixed apostrophe typo on home page
add docs JS to activate popover demos; fixes #13937
docs: minor correction to the focus-triggered popover demo explanation
regenerate docs.min.js

[skip sauce]
Merge pull request #13947 from twbs/fix-13937

Fix popover live demos in docs