updates and corrections

Author: Nick Grippin

Documents/cluster.md

@@ -19,12 +19,12 @@ The persistence cluster role contains actors responsible for tracking and persis
 
 ### Query
 
-This cluster role contains actors responsible for interacting with the backend database (currently Cassandra)
+This cluster role contains actors responsible for projecting data to a read-only database (currently Cassandra)
 
 ### Publication
 
-The publication role is responsible for creating and publishing the A&D reports from submitted LAR data
+The publication role is responsible for generating publication artifacts based on HMDA data (i.e. A&D reports, Modified LAR, etc.)
 
 ## Running cluster roles
 
-The configuration setting `"akka.cluster.roles"` in `cluster/src/main/resources/application.conf` defines which cluster roles will start when the HMDA Platform starts.  By default, all four roles are set to start at the same time, but this can be changed to any single role or combination of roles.  Currently, this can only be done from within the config file; there is no environment variable override.
+The configuration setting `"akka.cluster.roles"` in `cluster/src/main/resources/application.conf` defines which cluster roles will start when the HMDA Platform starts.  By default, all four roles are set to start at the same time, but this can be changed to any single role or combination of roles.  Setting the `HMDA_CLUSTER_ROLES` environment variable will allow you to decide which roles to spin up.