refactor(material/icon): provides context for undoing previous fix

Updates notation to style change in icon.scss which undoes a previous
bug fix for GH issue #11826. As this change is now deemed as an
accessibility issue due to it being cut off/hidden.

Fixes b/250063405

BREAKING CHANGE: undoes hiding icon overflow

Reverts icon having its overflow visible to be more accessible.

Author: essjay05

src/material/icon/icon.scss

@@ -41,7 +41,9 @@ mat-icon {
   }
 
   // Makes button icon overflow visible to fix b/250063405
-  // Apply styles to avoid applying text-spacing to .mat-icon
+  // Undoes previous fix to Issue #11826 in preference of
+  // fixing to improve accessibility by not having the icon
+  // get cut off
   overflow: visible;
 }