patch 8.1.1726: the eval.txt help file is too big

Problem:    The eval.txt help file is too big.
Solution:   Split off testing support to testing.txt.  Move function details
            to where the functionality is explained.

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1726,
 /**/
     1725,
 /**/