Updating Readme with more detailed instructions.

Hello luc!  I'm a software engineer working on getting your latest source running on my printer.  It has been pretty tricky trying to cobble together all the needed information, so I figured I would make my first contribution cleaning up and extending your current documentation.  I would eventually like to collaborate by sending future pull requests for you to update your repo as the definitive source if that is ok with you.  I still need to calibrate my X, Y, Z axis and extruder before I can get my first test print out.  I feel like I am pretty close at this point though.
Yup.  I noticed that in one of your commits.  I figured I would call it out in the install notes for those that didn't think there would be any calibration involved.  It may be a good idea to mention that in the read me as well.  I can write a note about that later today.