Make the README better

[avoidwork]

Feedback from a colleague:

"Your description of the library is cute but way too short. What the does "partially persistent" mean? What is the intent of this library? How does it differ from conventional ones. What are use-case scenarios that it is intended to resolve? The example is not a good example. It shows how you can make calls, but doesn't give a user friendly example using a scenario of object manipulation that is easy to grasp. The actual API section is OK in that the api calls are described, though minimally)."

This is quite useful because he has no practical experience with the language and is not biased.