Update README.md
Merge pull request #171 from pywebdesign/master

Update  README.md, Fix a typo
Added a section for transitions

I was a bit confused about having multiple transitions.  After figuring it out, I added this section.
correct wrong events in the inspection section of the README
Merge pull request #175 from danlo/master

Added a section for transitions
Merge branch 'master' into aasm4
instance-based events inspection now returns event instances (instead of the event names as symbol)