Update/add to various brief docs shown when user does genome --help, genome model --help, etc

I have been working on some tutorials on how to use the GMS.  These start from the beginning with a basic introduction to the genome tree.  Including things like `genome --help`, `genome model --help`, etc.  I noticed some typos, missing entries, etc. and started to fill these in.  

This pull request involves changes to `doc => description` lines only.

Something I noticed that would also be nice to resolve as part of this PR (perhaps) is that various places throughout the GMS help docs, probably when no doc is available, the following documentation is being used instead:  "Mixin that gives commands color option"

For example, under `genome model build --help` you see this for the `determine-error` sub-command, and the `heartbeat-check` sub-command.

In other places we see something more helpful like this:
"no description!!!: define 'doc' in the class definition for Genome::Model::Build::Command::ShowWorkflow"