Update Readme.md to clarify disconnect behavior.

Clarify the disconnect behavior with Pool, and the error POOL_NOEXIST.

Author: datvong-wm

Readme.md

@@ -579,7 +579,7 @@ Re-connecting a connection is done by establishing a new connection. Once
 terminated, an existing connection object cannot be re-connected by design.
 
 With Pool, disconnected connections will be removed from the pool freeing up
-space for a new connection to be created on the next getConnection call.
+space for a new connection to be created on the next getConnection call.  If all connections die, the cluster node will be removed.  If a database is restarted or temporarily offline, a `POOL_NOEXIST` error may occur.  This includes the auto-named cluster node.  If `restoreNodeTimeout` > 0, the cluster goes into an `offline` state until a successful connection can be established.  
 
 ## Performing queries