fix(docs) - Popovers MDX typo

Author: Lise LaTorre

ui/components/popovers/docs.mdx

@@ -184,7 +184,7 @@ This is due to the focus moving and trapping nature of non-modal dialogs. You **
   {getDisplayElementById(ErrorExamples.examples, 'with-footer')}
 </CodeView>
 
-### Warining
+### Warning
 
 <CodeView>
   {WarningExamples.default}