add redirect

Author: mongoKart

config/redirects

@@ -16,3 +16,5 @@ raw: ${prefix}/get-started/download-and-install/ -> ${base}/current/get-started/
 [*-master]: ${prefix}/${version}/connect/connection-pools/ -> ${base}/${version}/connect/connection-options/#connection-pools
 [v4.7-*]: ${prefix}/${version}/get-started/connect-to-mongodb -> ${base}/${version}/get-started/run-sample-query/
 
+# temp redirect until DOP deletes unversioned URLs
+[*-master]: ${prefix}/compatibility/ -> ${base}/current/compatibility/