Update description of AddTask enhancement in Developer Guide

[jayrometan]

Developer Guide:

Each member should describe the implementation of at least one enhancement she has added (or planning to add).
Expected length: 1+ page of technical content per person
The description can contain things such as,
How the feature is implemented.
Why it is implemented that way.
Alternatives considered.
The stated objective is to explain the implementation to a future developer, but a hidden objective is to show evidence that you can document deeply-technical content using prose, examples, diagrams, code snippets, etc. appropriately. To that end, you may also describe features that you plan to implement in the future, even beyond v1.4 (hypothetically).