doc: Specify when ssl_prefer_server_ciphers was added

The ssl_prefer_server_ciphers setting is quite important from a
security point of view, so simply stating that older versions
doesn't have it isn't very helpful.  This adds the version when
the GUC was added to help readers.

Backpatch to all supported versions since this setting has been
around since 9.4.

Reviewed-by: Peter Eisentraut 
Reviewed-by: Tom Lane 
Discussion: https://postgr.es/m/5D7E0F5E-E620-4D54-8788-66D421AC76F0@yesql.se
Backpatch-through: v12

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index ae8c3c6dd6ff1a005c14e20acc7ab0116bf7cb55..5cf342191885a7f6fdb04a20b499e487af4127b0 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -1427,11 +1427,11 @@ include_dir 'conf.d'
        
 
        
-        Older PostgreSQL versions do not have this setting and always use the
-        client's preferences.  This setting is mainly for backward
-        compatibility with those versions.  Using the server's preferences is
-        usually better because it is more likely that the server is appropriately
-        configured.
+        PostgreSQL versions before 9.4 do not have
+        this setting and always use the client's preferences.  This setting is
+        mainly for backward compatibility with those versions.  Using the
+        server's preferences is usually better because it is more likely that
+        the server is appropriately configured.