lang: adjust for-loop diagnostic wording

lang/diag.c

@@ -20,8 +20,9 @@ static const struct ivy_diag_msg diag_msg[] = {
 	MSG(IVY_LANG_MSG_DO_UNEXPECTED_IN_INLINE_FOR,
             "`[yellow]do[reset]` is not used in inline for-loops."),
 	MSG(IVY_LANG_MSG_PREVIOUS_EXPRESSION_IS_FOR_BODY,
-            "the previous expression is used as the for-loop body. perhaps you "
-            "forgot a [blue]statement separator[reset]?"),
+            "the expression before `[yellow]for[reset]` is used as the "
+            "for-loop body. perhaps you forgot a [blue]statement "
+            "separator[reset]?"),
 };
 static const size_t nr_diag_msg = sizeof diag_msg / sizeof diag_msg[0];