remove reference to jumbo build

Bug: 994387
Change-Id: I0c675bb6aca04d64593de420c7936cb88ff6a051
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2334503
Commit-Queue: Dirk Pranke <dpranke@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
diff --git a/compile_single_file.py b/compile_single_file.py
index 9c99521..833e03e 100644
--- a/compile_single_file.py
+++ b/compile_single_file.py
@@ -40,10 +40,7 @@
       required=True)
   parser.add_argument(
       '--build-dir',
-      help='The build directory, relative to the source directory. Jumbo '
-           'builds aren\'t supported but you can create a non-jumbo build '
-           'config just for this script and keep using jumbo in your regular '
-           'builds.',
+      help='The build directory, relative to the source directory.',
       required=True)
 
   options = parser.parse_args()