README.md text conflicts with LICENCE

[brett060102]

The LICENCE was updated about 4 years ago to move to a stock Apache License 2.0.
But the README.MD file was not updated to account for the change. It still contains the text:

Gorgonia and the tensor package are licenced under a variant of Apache 2.0. It's for all intents and purposes the same as the Apache 2.0 Licence, with the exception of not being able to commercially profit directly from the package unless you're a Significant Contributor (for example, providing commercial support for the package).

This conflict places the licencing of gorgonia/ tensor is state of legal ambiguity and should be addressed.