tools: update alternative docs versions

Add `11.x` and mark `10.x` as `lts`.

PR-URL: #23980
Reviewed-By: Refael Ackermann <[email protected]>
Reviewed-By: Vse Mozhet Byt <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>

tools/doc/html.js

@@ -168,6 +168,8 @@ function altDocs(filename) {
   }
 
   const versions = [
+    { num: '11.x' },
+    { num: '10.x', lts: true},
     { num: '9.x' },
     { num: '8.x', lts: true },
     { num: '7.x' },