Release v4.3.0 (#28228)

* Prep for v4.3.0

* More updates for v4.3.0.

* rerun to build docs source map

site/docs/4.3/components/breadcrumb.md

@@ -0,0 +1,58 @@
+---
+layout: docs
+title: Breadcrumb
+description: Indicate the current page's location within a navigational hierarchy that automatically adds separators via CSS.
+group: components
+---
+
+## Example
+
+{% capture example %}
+<nav aria-label="breadcrumb">
+  <ol class="breadcrumb">
+    <li class="breadcrumb-item active" aria-current="page">Home</li>
+  </ol>
+</nav>
+
+<nav aria-label="breadcrumb">
+  <ol class="breadcrumb">
+    <li class="breadcrumb-item"><a href="#">Home</a></li>
+    <li class="breadcrumb-item active" aria-current="page">Library</li>
+  </ol>
+</nav>
+
+<nav aria-label="breadcrumb">
+  <ol class="breadcrumb">
+    <li class="breadcrumb-item"><a href="#">Home</a></li>
+    <li class="breadcrumb-item"><a href="#">Library</a></li>
+    <li class="breadcrumb-item active" aria-current="page">Data</li>
+  </ol>
+</nav>
+{% endcapture %}
+{% include example.html content=example %}
+
+## Changing the separator
+
+Separators are automatically added in CSS through [`::before`](https://developer.mozilla.org/en-US/docs/Web/CSS/::before) and [`content`](https://developer.mozilla.org/en-US/docs/Web/CSS/content). They can be changed by changing `$breadcrumb-divider`. The [quote](https://sass-lang.com/documentation/Sass/Script/Functions.html#quote-instance_method) function is needed to generate the quotes around a string, so if you want `>` as separator, you can use this:
+
+```scss
+$breadcrumb-divider: quote(">");
+```
+
+It's also possible to use a **base64 embedded SVG icon**:
+
+```scss
+$breadcrumb-divider: url(data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSI4IiBoZWlnaHQ9IjgiPjxwYXRoIGQ9Ik0yLjUgMEwxIDEuNSAzLjUgNCAxIDYuNSAyLjUgOGw0LTQtNC00eiIgZmlsbD0iY3VycmVudENvbG9yIi8+PC9zdmc+);
+```
+
+The separator can be removed by setting `$breadcrumb-divider` to `none`:
+
+```scss
+$breadcrumb-divider: none;
+```
+
+## Accessibility
+
+Since breadcrumbs provide a navigation, it's a good idea to add a meaningful label such as `aria-label="breadcrumb"` to describe the type of navigation provided in the `<nav>` element, as well as applying an `aria-current="page"` to the last item of the set to indicate that it represents the current page.
+
+For more information, see the [WAI-ARIA Authoring Practices for the breadcrumb pattern](https://www.w3.org/TR/wai-aria-practices/#breadcrumb).