patch 8.2.2388: no easy way to get the maximum or mininum number value

Problem:    No easy way to get the maximum or mininum number value.
Solution:   Add v:numbermax and v:numbermin.

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2388,
 /**/
     2387,
 /**/