Merge branch 'fix/badge-default-colors' of https://github.com/jonwolski/bootstrap into jonwolski-fix/badge-default-colors

1. Instead of having two selectors, we use the `.list-group-item` class and have coverage for list items and anchors.
2. Rather than override all border values, we only override what we set with `border-top`.

I never use this dang list and it just falls out of date far too easily. Dropping for my own sanity.

Fixes #23360 by restoring just the offset class generation to our grid
framework mixins. Also restores the `make-col-offset` mixin.

Docs have been restored to illustrate this behavior and merged with the
newer margin utilities examples.

I suggest removing `color: #FFF` from the `badge` class, because it is
provided by the `badge-<modifier>` classes along with a
background-color, whereas there is no corresponding background-color
provided on the `badge` class itself.

Background
----------

According to the documentation:

> [badge] Requires one of the contextual, color modifier classes for `color` and
> `background-color`.

That is, color and background color should be provided by a modifier
class, rather than the badge class itself.

e.g. `<span class='badge badge-primary'>4</span>`

In general, providing a `color` property without also providing a
`background-color` should be avoided. [W3 QA tips]

In this context, this is a problem only if someone creates a `badge`
without providing a modifier. Such an omition may be difficult to trouble-shoot,
because this will most likely yield white text on a white background.

[W3 QA tips](https://www.w3.org/QA/Tips/color)

It was removed in 6d64afe5.

Reduce liquid's whitespace for a few pages and move about menu to the end.

Also fix a couple of typos while at it and change header tags' order.

docs: New favicons and add a service worker