Update documentation for "with state" method

[dmitry-zaets]

With redux-things/redux-actions-assertions-js#3 "with state" function now supports function.
Docs needed to be updated:

• chai
  • Update function definition
  • Add example of usage
• expect
  • Update function definition
  • Add example of usage
• expect.js
  • Update function definition
  • Add example of usage
• should
  • Update function definition
  • Add example of usage

Related: #9