Field/Type descriptions from schema could be added to the generated code.

[strue36]

This will presumably result in a similar discussion to this. jhnnsrs/turms#54

I've implemented this as docstrings on a local branch using similar logic to that used in turms.

[strue36]

I originally thought that this is what the include_comments flag was for.

[mat-sop]

I think optional descriptions could be added to the generated code, but first, we should clarify the include_comments description in the readme.

[mat-sop]

To give more context, we're using ast to generate python code, but in this library there is no way to represent comments. So adding descriptions in form of comments is quite difficult, but we still can do it like turms - using docstrings or description= attribute.