Add support for documenting modules

Problem/Motivation

As a site historian I would like to know why a module was added is required. It should be added as an option for documentable entities even though it is not really an entity.

Any enabled modules should appear in the list of items that can be documented.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

1. Pathing should be at /admin/modules/documents/project/[submodule] *submodule is optional.
2. Adds an option checkbox to document modules.
3. Modules and submodules will show up in the select list of things to document (if the option has been set to document modules)

API changes

Data model changes