Fix typo in changeset

Author: acmertz

.changeset/gentle-cobras-punch.md

@@ -2,4 +2,4 @@
 '@shopify/polaris': patch
 ---
 
-Updated the focus helper functions to no longer treat buttons with `aria-disabled="disabled"` and `tabindex="-1" (but no`disabled` attribute) as focusable.
+Updated the focus helper functions to no longer treat buttons with `aria-disabled="true"` and `tabindex="-1" (but no`disabled` attribute) as focusable.