Extension Support with Logging Example

NOTE: This release is a documentation enhancement only. The API is NOT impacted in any way.

1. The Dev Guide was refined to include Extending astx-redux-util along with an extensive Logging Extension section, showing how reducerHash() can play a key roll in implementing a centralized reducer-based logging utility.

2. A Most Excellent Example was streamlined, replacing the placeboReducer with an anonymous arrow function.