Clarify that values drawn produce a discrete uniform distribution, and not for example a normal (or bell shaped) distribution. I intend to implement a random physics sensor which will return a bell distribution and this edit will avoid confusion.
* Document update frequency
Documented that the random number changes every 30 seconds
according to http://fabian-affolter.ch/blog/random-sensor/
* Learned the source of the 30s polling frequency
