docs(badge): add icon indicator text for screen-reader in example (#15115)

Author: Suresh918

src/material-examples/badge-overview/badge-overview-example.html

@@ -13,5 +13,9 @@
 <p>
   Icon with a badge
   <mat-icon matBadge="15" matBadgeColor="warn">home</mat-icon>
+    <!-- Include text description of the icon's meaning for screen-readers -->
+    <span class="cdk-visually-hidden">
+      Example with a home icon with overlaid badge showing the number 15
+    </span>
 </p>