README.md is incomplete and doesn't link to http://www.gravizo.com/

[Adam Spiers]

http://www.gravizo.com/ is a very nice homepage which is full of helpful information and provides a fairly comprehensive explanation of what gravizo can do, and how to use it, including both direct and indirect techniques. However unfortunately the github README.md is much less comprehensive (it doesn't even explain the direct method), and it doesn't link to http://www.gravizo.com/.

IMHO it doesn't make sense to have two sets of documentation where one is incomplete. So I would suggest removing one set and making it simply link to the other location, so that there is a single source of truth which will be comprehensive and accurate.

[Adam Spiers]

Additionally the documentation on http://www.gravizo.com/ is out of date and incorrect as reported in #37, so that's another reason to unify the docs into a single location.

[Hugo Freire Gil]

Thanks @aspiers, I will take a look.