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.
diff --git a/src/version.c b/src/version.c
index afdefb2..a1d68d8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1726,
+/**/
     1725,
 /**/
     1724,