patch 8.2.1281: the "trailing characters" error can be hard to understand

Problem:    The "trailing characters" error can be hard to understand.
Solution:   Add the trailing characters to the message.
diff --git a/src/cmdhist.c b/src/cmdhist.c
index d708535..69c83c0 100644
--- a/src/cmdhist.c
+++ b/src/cmdhist.c
@@ -705,7 +705,7 @@
 	    else
 	    {
 		*end = i;
-		emsg(_(e_trailing));
+		semsg(_(e_trailing_arg), arg);
 		return;
 	    }
 	}
@@ -717,7 +717,7 @@
 	end = arg;
     if (!get_list_range(&end, &hisidx1, &hisidx2) || *end != NUL)
     {
-	emsg(_(e_trailing));
+	semsg(_(e_trailing_arg), end);
 	return;
     }