Fixing terminoloty/actions section in documentation
Fixing terminoloty/actions section in documentation

* Changed the order of description for synchronous and asynchronous
  actions according to the attached picture.
* Shortened text lines to fit 80 characters limit.

Change-Id: I1e6810816cb3490f9347bc6a85b59af4e5e467ca

openstack/mistral,StackStorm/mistral,StackStorm/mistral,openstack/mistral