move popover examples heading to directly before the actual examples
move scrollspy callouts so they're all adjacent to each other
Merge pull request #15091 from twbs/popovers-heading

move popover examples heading to directly before the actual examples
Merge pull request #15092 from twbs/scrollspy-callouts

move scrollspy callouts so they're all adjacent to each other
[skip sauce]
grunt
give all docs callouts IDs