Standardize header, footer, and content language

[vmike245]

Currently there is not a standard with how bootstrap refers to the header, footer, and content of an element. There are at least 4 items which fall into this category:

• Tooltips
  • Content: tooltip-inner
• Modals
  • Header: modal-header
  • Content: modal-body
  • Footer: modal-footer
• Card
  • Header: card-header
  • Content: card-block
  • Footer: card-footer
• Popover
  • Header: popover-title
  • Content: popover-content

For the most part the header and footer format is the same, but the content section seems to be on a per component basis. I would suggest standardizing the language around these sections to improve discoverability. If a user who has used cards before tries to use a modal, the first things they will try is modal-header, modal-block, modal-footer since that is what they used for card. Currently only 2 out of 3 of those will work. I think everyone would agree that a discoverable API is a very important part of a successful service and drastically improves ease of use.

[bkdotcom]

I vote for "body" (which is semantically similar to table markup: <thead>,<tbody>, & <tfoot>)

[Oxicode]

+1 body

[mdo]

Two PRs coming in #22828 and #22829 to update popover and card classes to match the modals. No changes to the tooltips given that's an odd one.