Added alerta housekeeping settings

DEFAULT_EXPIRED_DELETE_HRS = 2  # hours (0 hours = do not delete)
DEFAULT_INFO_DELETE_HRS = 12  # hours (0 hours = do not delete)

Related: PROD-37066
Change-Id: Id7dfc0de969c5ae8d3a5e277f95b5fe1a2212598
diff --git a/README.rst b/README.rst
index 42ce26d..08a2308 100644
--- a/README.rst
+++ b/README.rst
@@ -170,6 +170,18 @@
     server:
       is_container: false
 
+Set alerta housekeeping default timeouts
+----------------------------------------
+
+.. code-block:: yaml
+
+parameters:
+  prometheus:
+    alerta:
+      housekeeping:
+        default_expired_delete_hrs: 2160
+        default_info_delete_hrs: 2160
+
 
 Documentation and Bugs
 ======================