patch 7.4.1684

Problem:    README text is slightly outdated.
Solution:   Mention the READMEdir directory.

src/version.c

@@ -748,6 +748,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1684,
 /**/
     1683,
 /**/