Update _redirects

Author: ryanfoxtyler

public/_redirects

@@ -2,4 +2,4 @@
 /docs/badger/*         https://badger-docs.netlify.app/:splat 200!
 
 /docs/dgraphcloud/*    /docs/cloud/:splat 301!
-/v*                    /docs/v:splat 200!
+/docs/v21.03/*         https://release-v21-03--dgraph-docs-repo.netlify.app/docs/v21.03/:splat 200!