patch 7.4.900

Problem:    README file can still be improved
Solution:   Add a couple of links. (Christian Brabandt)

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    900,
 /**/
     899,
 /**/