Scheduled maintenance window announcement (#5491)

Author: kimsauce

docusaurus.config.js

@@ -245,6 +245,12 @@ module.exports = {
         name: 'msvalidate.01', content: 'BA6FBE48309F6E1CFFD055E769857586'
       },
     ],
+    announcementBar: {
+      id: 'maintenance',
+      content: 'Help Docs will undergo scheduled maintenance on Fri, 6/27 from 5-6 PM PT. Service may be briefly disrupted. We apologize for any inconvenience.',
+      backgroundColor: '#fafbfc',
+      textColor: '#091E42',
+    },
     imageZoom: {
       selector: '.markdown :not(a) > img',
       // Optional medium-zoom options