Javadocs for JMSContext#start should mention that it is usually called automatically

The [javadocs for JMSContext#start](https://jms-spec.java.net/2.0/apidocs/javax/jms/JMSContext.html#start%28%29) could be improved by mentioning that it is not normally necessary for applications to call this method, since the the underlying connection used by the JMSContext will be started automatically when a consumer is created.

The javadocs for JMSContext#createConsumer, JMSContext#createSharedConsumer and JMSContext#createSharedDurableConsumer should also mention this.
#### Affected Versions
[2.0, JMS 2.0 rev A]

Start with the JMSContext Javadocs linked in the issue and review start(), createConsumer(), createSharedConsumer(), and createSharedDurableConsumer(). Done means each relevant method explains that applications usually do not need to call start() because creating a consumer starts the underlying connection automatically.

Written by the indexing model from the issue text.