Remove hint to use "git help -a"

The newbie user will run away screaming when they see all possible
commands.  The expert user will already know about the -a option from
reading the git man page.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

help.c

@@ -238,7 +238,6 @@ void list_common_cmds_help(void)
 		mput_char(' ', longest - strlen(common_cmds[i].name));
 		puts(common_cmds[i].help);
 	}
-	puts("(use 'git help -a' to get a list of all installed git commands)");
 }
 
 static void show_man_page(const char *git_cmd)