Disable cloud-init rootfs resize to prserve disk size configured by MAAS

Prod-Related: PROD-36317
Change-Id: I7319bd3f00ea66c0663a26087bee20558990026a
diff --git a/README.rst b/README.rst
index 57ac725..7490b79 100644
--- a/README.rst
+++ b/README.rst
@@ -538,6 +538,9 @@
             kernel_package:
               enabled: true
               value 'linux-image-virtual-hwe-16.04'
+            # disable cloud-init rootfs resize to prserve disk size configured by MAAS
+            rootfs_resize:
+              disabled: true
 
 Single MAAS cluster service [multiple racks]