Update compatibility.adoc

Author: RichardSmedley

modules/project-docs/pages/compatibility.adoc

@@ -140,17 +140,19 @@ It is best to upgrade either the SDK or the Couchbase version you are using.
 .Recommended SDK per Server Version Matrix
 [#table_sdk_versions]
 |===
-| | 3.4, 3.5 | 3.6, 3.7 | 3.8
+| | 3.4, 3.5 | 3.6, 3.7 | 3.8 | 3.9
 
 | *Server 7.0 - 7.2*
 | *✔*
 | *✔*
 | *✔*
+| *✔*
 
 | *Server 7.6*
 | *✔*
 | *✔*
 | *✔*
+| *✔*
 |===
 
 Note the https://www.couchbase.com/support-policy[End of Life dates^] for Couchbase Server and SDK versions.