JAVA-3142: Improving the documentation for remote local dc's feature

patch by Nitin Chhabra; reviewed by Bret McGuire for JAVA-3142

Author: nitinitt

core/src/main/resources/reference.conf

@@ -574,7 +574,9 @@ datastax-java-driver {
       # Modifiable at runtime: no
       # Overridable in a profile: yes
       allow-for-local-consistency-levels = false
+      
       # Ordered preference list of remote dc's (in order) optionally supplied for automatic failover. While building a query plan, the driver uses the DC's supplied in order together with max-nodes-per-remote-dc
+      # Users are not required to specify all DCs, when listing preferences via this config
       # Required: no
       # Modifiable at runtime: no
       # Overridable in a profile: no