Update version labels in docusaurus.config.js

Removed beta label from version 21 R3 and cleaned up version entries.

Author: arnaud4d

docusaurus.config.js

@@ -238,14 +238,10 @@ sidebarItemsGenerator: async function (args) {
 },
           versions: {
               '21-R3': {
-              label: '21 R3 BETA',
+              label: '21 R3',
               banner: 'none',
             },
-              '21-R2': {
-              label: '21 R2',
-              banner: 'none',
-            },
-              '21': {
+            '21': {
               label: '21',
               banner: 'none',
             },