t5516 (fetch-push): update test description

The file was originally created in bcdb34f (Test wildcard push/fetch,
2007-06-08), and only contained tests that exercised wildcard
functionality at the time.  In subsequent commits, many other tests
unrelated to wildcards were added but the test description was never
updated.  Fix this.

Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5516-fetch-push.sh

@@ -1,6 +1,17 @@
 #!/bin/sh
 
-test_description='fetching and pushing, with or without wildcard'
+test_description='Basic fetch/push functionality.
+
+This test checks the following functionality:
+
+* command-line syntax
+* refspecs
+* fast-forward detection, and overriding it
+* configuration
+* hooks
+* --porcelain output format
+* hiderefs
+'
 
 . ./test-lib.sh