* Fix docs for heading sizes (sizes here were from v3)
* Added rem sizes to header size docs
* Fixed erroneous px sizes

* Add .img-fluid to card images in columns to ensure proper resizing
* change that variable from regular value to variable
* use calc to figure out a tighter border for card images

Cards must be inline-block in columns, otherwise they can get split across columns

[ci skip]

Closes #20507

[skip sauce]

For the sake of cleanliness.

- Update docs examples to use newer .form-check suite of classes
- Update form validation mixin to use newer classes as well

Fixes #20484

To be prefixed with `.table-`.

See: https://github.com/twbs/bootstrap/pull/18255#issuecomment-237034763

Fix README badge alignment.

Updated docs with extra auto resize example

Added information about the .panel-group class

v4: Split dropup button example

Update package.json to remove jspm ignore

Fix package.json

Fixes #20495

v4: Remove media margin

Remove unnecessary swearing in docs/forms.md