doc: Add note to use a stable Celadon source tree
So far the patches are only suite for Celadon Android 9.
Need to specify the Android 9 repo branch to apply patches and
build Celadon image.
@@ -31,6 +31,12 @@ Build Celadon from source
<https://01.org/projectceladon/documentation/getting_started/build-source>`_ guide
to set up the Celadon project source code.
+ .. note:: The master branch is based on Google Android 10 Pre-Production Early Release.
+ We should use following command to specify a stable Celadon branch based on the Google
+ Android 9 source code in order to apply those patches in the :ref:`ACRN patch list`::
+
+ $ repo init -u https://github.com/projectceladon/manifest.git -b celadon/p/mr0/master -m stable-build/ww201925_H.xml
+
#. Select Celadon build target::
$ cd <Celadon project directory>
