Deprecate default package installation for publishers

Since Pike in order to install package for publisher,
pkg field for publisher should be defined.

Change-Id: I4ca7004c322c1ab073934761563e88c1559cf37b
Related-Prod: https://mirantis.jira.com/browse/PROD-20427
diff --git a/README.rst b/README.rst
index a7bab40..23d6b1b 100644
--- a/README.rst
+++ b/README.rst
@@ -148,6 +148,22 @@
             host: 10.0.0.1
             port: 2003
 
+Since Pike release in order to install package for publisher, publisher definition should
+have pkg field explicitly set to needed package:
+
+.. code-block:: yaml
+
+    ceilometer:
+      server:
+        enabled: true
+        publisher:
+          example_publisher:
+            enabled: true
+            url: publisher_url://
+            pkg: publisher-pkg-name
+
+
+
 Ceilometer compute agent
 ------------------------