Add a CONTRIBUTING.md to clarify project structure and valid contributions (#550)

* Add a recommended project stucture
* Add description for languages with more than one unit testing framework

README.md

@@ -17,9 +17,6 @@ Alternatively, use the Approval tests provided in this repository. (Read more ab
 
 The idea of the exercise is to do some deliberate practice, and improve your skills at designing test cases and refactoring. The idea is not to re-write the code from scratch, but rather to practice taking small steps, running the tests often, and incrementally improving the design. 
 
-Please don't send me a pull request with your solution. It can be a bit confusing since GitHub encourages you to do so! Please only send me pull requests if you have a correction or improvement to the starting position. You don't want to spoil the fun of doing the exercise for other people!
-
-
 ### Gilded Rose Requirements in other languages 
 
 - [English](GildedRoseRequirements.md)
@@ -49,17 +46,8 @@ As Bobby Johnson points out in his article ["Why Most Solutions to Gilded Rose M
 better practice at handling a legacy code situation if you do this Kata in the original C#. However, I think this kata
 is also really useful for practicing writing good tests using different frameworks and approaches, and the small changes I've made help with that. I think it's also interesting to compare what the refactored code and tests look like in different programming languages.
 
-## Translating this code
-
-More translations are most welcome! I'm very open for pull requests that translate the starting position into additional languages. 
-
-Please note a translation should ideally include:
-
-- a translation of the production code for 'update_quality' and Item
-- one failing unit test complaining that "fixme" != "foo"
-- a TextTest fixture, ie a command-line program that runs update_quality on the sample data for the number of days specified.
-
-Please don't write too much code in the starting position or add too many unit tests. The idea with the one failing unit test is to tempt people to work out how to fix it, discover it wasn't that hard, and now they understand what this test is doing they realize they can improve it.  
-
-If your programming language doesn't have an easy way to add a command-line interface, then the TextTest fixture is probably not necessary.
+## Contributing
 
+Contributions are encouraged! You could add a translations of the specification
+in another language or a new starting point for your favorite programming
+language. Please see [CONTRIBUTING.md](./CONTRIBUTING.md) for more details.