Update to readme.md in 'make migrate' section (#245)
Update to readme.md in 'make migrate' section (#245)

* Changed the section regarding 'make migrate' to suggest to users what to do if they see an error

* Updated readme file to advise users about error messages after running 'make migrate'

chicagopython/chipy.org,chicagopython/chipy.org,chicagopython/chipy.org,chicagopython/chipy.org