Tighten comment

Author: danielballan

Containerfile

@@ -86,9 +86,8 @@ ARG APP_UID=999
 # Add the application virtualenv to search path.
 ENV PATH=/app/bin:$PATH
 
-# We will run the app as a user 'app' with a configurable uid. The default uid
-# is pinned to 999, at the high end of the system range.
-# system range.
+# We will run the app as a user 'app' with a stable uid that is
+# configurable via an ARG.
 RUN set -ex && \
     groupadd -r -g ${APP_UID} app && \
     useradd -r -d /app -g app -u ${APP_UID} -N app