Add docs for .w-100 utility class

[skip sauce]

diff --git a/docs/components/utilities.md b/docs/components/utilities.md
index 76bf5f9bedef8196433aec49bb6fea0094ba9d50..829ee49078e68daeca845b0ebce92b68da365d7e 100644 (file)
--- a/docs/components/utilities.md
+++ b/docs/components/utilities.md
@@ -165,6 +165,14 @@ Sometimes contextual classes cannot be applied due to the specificity of another
 {% capture callout-include %}{% include callout-warning-color-assistive-technologies.md %}{% endcapture %}
 {{ callout-include | markdownify }}
 
+## Widths
+
+Easily make an element as wide as its parent using the `.w-100` utility class, which sets `width: 100%`.
+
+{% example html %}
+<img class="w-100" data-src="holder.js/200px100?outline=yes&text=Width%20%3D%20100%25" alt="Width = 100%">
+{% endexample %}
+
 ## Close icon
 
 Use a generic close icon for dismissing content like modals and alerts. **Be sure to include text for screen readers**, as we've done with `aria-label`.