Add documentation of available steps

[oniric85]

Hi, I'm a new Behat and Mink user and I'm having a difficult time finding out the steps provided by the MinkExtension. A simple page with a list of the steps and their parameters would come handy for a newcomer. Thanks!

[spolischook]

It's impossible to maintain documentation somewhere outside the code. However code is very good documented, try:

bin/behat -dl
bin/behat -di