Revert "add skipnav link in header"

src/Header.messages.jsx

@@ -91,11 +91,6 @@ const messages = defineMessages({
     defaultMessage: 'Secondary',
     description: 'The aria label for the seconary nav',
   },
-  'header.label.skip.nav': {
-    id: 'header.label.skip.nav',
-    defaultMessage: 'Skip to main content',
-    description: 'A link used by screen readers to allow users to skip to the main content of the page.',
-  },
 });
 
 export default messages;