Documentation of messages and how they should be used (overview)

[cookeac]

We noted that some brief documentation of how to use each of the messages would be helpful. This is not a list of individual fields which should be autogenerated so that it is maintained.

[cookeac]

Steps:

1. Define a structure for how we will document each message (how it should be used, and things that don't fit in a single line description)
2. List the messages and split these between us for writing.

Target is people implementing but not developers (e.g. designers, animal recording specialists, etc)