gitcli: formatting fix

The paragraph to encourage use of "--" in scripts belongs to the
bullet point that describes the behaviour for a command line without
the explicit "--" disambiguation; it is not a supporting explanation
for the entire bulletted list, and it is wrong to make it a separate
paragraph outside the list.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/gitcli.txt

@@ -37,7 +37,7 @@ arguments.  Here are the rules:
    file called HEAD in your work tree, `git diff HEAD` is ambiguous, and
    you have to say either `git diff HEAD --` or `git diff -- HEAD` to
    disambiguate.
-
++
 When writing a script that is expected to handle random user-input, it is
 a good practice to make it explicit which arguments are which by placing
 disambiguating `--` at appropriate places.