feat(groups/{_,k,n,p}*): vim syntax support

Add vim modeline instructing the editor to use syntax plugin provided by apparmor.
Continuation of #394 to keep the diff list relatively short.

apparmor.d/groups/network/openvpn

@@ -125,3 +125,5 @@ profile openvpn @{exec_path} flags=(attach_disconnected) {
 
   include if exists <local/openvpn>
 }
+
+# vim:syntax=apparmor