xtensa-build-zephyr.py: change help for -d, just say it like it is

Make sure users do not misinterpret our single `debug_overlay.conf` file
as some kind of complex and elaborate "debug build" concept. Also save
users who want to see the file a lot of time by naming it directly in
the --help.

Empty layers of indirection are just spurious obfuscation.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>

Author: marc-hb

scripts/xtensa-build-zephyr.py

@@ -161,7 +161,7 @@ def parse_args():
 	parser.add_argument("platforms", nargs="*", action=validate_platforms_arguments,
 						help="List of platforms to build")
 	parser.add_argument("-d", "--debug", required=False, action="store_true",
-						help="Enable debug build")
+						help="Shortcut for: -o sof/app/debug_overlay.conf")
 	parser.add_argument("-i", "--ipc", required=False, choices=["IPC4"],
 			    help="""Applies --overlay <platform>/ipc4_overlay.conf
 and a different rimage config. Valid only for IPC3 platforms supporting IPC4 too.""")