t1404: rename file to t1404-update-ref-errors.sh

I want to broaden the scope of this test file, so rename it accordingly.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1404-update-ref-errors.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-test_description='Test git update-ref with D/F conflicts'
+test_description='Test git update-ref error handling'
 . ./test-lib.sh
 
 test_update_rejected () {