patch 8.2.1436: function implementing :substitute has unexpected name

Problem:    Function implementing :substitute has unexpected name.
Solution:   Rename from do_sub() to ex_substitute().

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1436,
 /**/
     1435,
 /**/