Improve calling service example

Problem/Motivation

4. The example code for calling the bulletin queue service could use more explanation.
- a) setFromAddress() is shown with an actual email address, but it is actually a "from address ID" value that should be given. It's also optional and only needs to be provided if your GovDelivery account has multiple from addresses configured.
- b) setQueueUid() could explain this identifier is what is used with setFlag('dedupe', TRUE) to remove duplicates.
- c) setHeader() is also optional.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes