Added link to microservices article

[knoxknox]

This article describes some aspects of migration to microservices.
It described OOD, DI, SOLID, Law of Demeter, Service Objects, etc..

[knoxknox]

+@iJackUA
Hi, could you look at this PR ?

[rennanoliveira]

I think this is a great article, but the current section it is added to is focusing on creating smaller classes and following TRUE, SOLID classes. The medium article goes even further, getting into microservices. Perhaps we could have a section about microservices, and drop the link there.

[iJackUA]

Thanks, this article looks interesting.

I really want to think about it more and eventually to create a separate section for detailed explanation and links per each aspect of SOLID and GRASP #31.
There is a TODO Describe approaches like Form Model, Service Object, Context and this article touches a lot of these.

Note for me: Make a note about "law of demeter" and rewrite examples in section http://rwdtow.stdout.in/#mixin-composition to emphasize usage in private interface

http://www.virtuouscode.com/2011/07/05/demeter-its-not-just-a-good-idea-its-the-law/

[iJackUA]

I'll merge it for now and add an issue to process it with more details #34