Emphasize setting connectionClass

Author: cjbj

doc/api.md

@@ -265,15 +265,19 @@ String connectionClass
 ```
 
 The Connection class value defines a logical name for connections.
+Most single purpose applications should set `connectionClass` when
+using a connection pool or DRCP.
+
 When a pooled session has a connection class, Oracle ensures that the
 session is not shared outside of that connection class.
 
 The connection class value is similarly used by
 [Database Resident Connection Pooling](#drcp) (DRCP) to allow or
 disallow sharing of sessions.
 
+
 For example, where two different kinds of users share one pool, you
-might set ```connectionClass``` to 'HR' for connections that access a
+might set `connectionClass` to 'HR' for connections that access a
 Human Resources system, and it might be set to 'OE' for users of an
 Order Entry system.  Users will only be given sessions of the
 appropriate class, allowing maximal reuse of resources in each case,