patch 8.0.0511: message for skipping client-server tests is unclear

Problem:    Menuage for skipping client-server tests is unclear.
Solution:   Be more specific about what's missing (Hirohito Higashi, Kazunobu
            Kuriyama)
diff --git a/src/version.c b/src/version.c
index 08adb69..7d2cf27 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    511,
+/**/
     510,
 /**/
     509,