* Migration docs page for v5

* Add JS section, tweak some copy

* Update migration.md

This reverts commit 089e3334.

This reverts commit 1da5b9f7.

- Deletes mixin mentions from float docs
- Deletes mixin mention from visibility docs
- Deletes the image-replacement page for text-hide

- Drop hover and focus states
- Drop .badge-* variants and associated mixin for .bg-* utilities
- Drop .badge-pill for .rounded-pill utliity and adjust horizontal padding to find middle ground of .badge and old .badge-pill
- Remove unused variables
- Add default color value to .badge base class
- Update docs to reflect changes

This allows for the build to fail if a reference isn't found.

This happens because we have the section kind enabled (needed for examples).

This causes `p` tags which is invalid HTML.

No more Ruby dependency and most important more than 10 times less build time (at least on Windows)!