Might be nice to have the host in the example (#1118)

README.md

@@ -64,6 +64,7 @@ var config = {
   user: 'foo', //env var: PGUSER
   database: 'my_db', //env var: PGDATABASE
   password: 'secret', //env var: PGPASSWORD
+  host: 'localhost', // Server hosting the postgres database
   port: 5432, //env var: PGPORT
   max: 10, // max number of clients in the pool
   idleTimeoutMillis: 30000, // how long a client is allowed to remain idle before being closed