Elaborate on documentation

Problem/Motivation

Right now the Comment Notify documentation is pretty bare bones. It could use more explanation.

Steps to reproduce

Visit the current documentation at https://www.drupal.org/docs/extending-drupal/contributed-modules/contrib... →

Remaining tasks

1. Add info on configuration options
2. Add info on known bugs and workarounds
3. Add info on contributing to the project
4. Record a video tutorial