fixup! 672e41e1c5ceb488d08aa9166ce4b595a639693f

- Remove destroy button info
Fix incorrect count for heading children

Was initially counting the number of headings rather than the number
of categories inside each heading.
fixup! 3524fe1b2fa7a8732c47b1ad1fcb9bacaca6da4a

- Better clarification for deleting headings
Add JS confirmation for deleting heading/category