docs(client): improve the Client instance example (brianc#2935)

Author: samueldurantes

docs/pages/apis/client.mdx

@@ -34,6 +34,7 @@ const { Client } = require('pg')
 const client = new Client({
   host: 'my.database-server.com',
   port: 5334,
+  database: 'database-name',
   user: 'database-user',
   password: 'secretpassword!!',
 })