Demonstrate "createNodePort" with an example

[sabbyanandan]

As a user, while deploying a stream with http-source, I wasn't fully aware of how to enable to use the createNodePort property. Though the property appears in the table on the reference guide, I wasn't sure how to pass it at stream deployment.

We used to have an example in the docs before, but somehow that didn't get ported over entirely. It'd be good to demonstrate this capability in an FAQ or as a recipe.

Also, the createNodePort didn't show up in the deployer properties dialog window — see: spring-cloud/spring-cloud-dataflow#3801 — I am guessing it because this is not a true deployer property since we use the full-form property resolution for createNodePort.