Add a CONTRIBUTING.md doc

CONTRIBUTING.md

@@ -0,0 +1,54 @@
+# Contributing
+
+By participating to this project, you agree to abide our [code of
+conduct](/CODE_OF_CONDUCT.md).
+
+## Setup your machine
+
+`releaser` is written in [Go](https://golang.org/).
+
+Prerequisites are:
+
+* Build:
+  * `make`
+  * [Go 1.6+](http://golang.org/doc/install)
+
+Clone `releaser` from source:
+
+```sh
+$ git clone https://github.com/goreleaser/releaser.git
+$ cd releaser
+```
+
+Install the build and lint dependencies:
+
+``` sh
+$ make setup
+```
+
+A good way of making sure everything is all right is running the test suite:
+
+``` sh
+$ make test
+```
+
+## Test your change
+
+You can create a branch for your changes and try to build from the source as you go:
+
+``` sh
+$ go build
+```
+
+When you are satisfied with the changes, we suggest you run:
+
+``` sh
+$ make ci
+```
+
+Which runs all the linters and tests.
+
+## Submit a pull request
+
+Push your branch to your `releaser` fork and open a pull request against the
+master branch.

README.md

@@ -108,6 +108,10 @@ class Release < Formula
 end
 ```
 
+## How to contribute
+
+Please refer to our [contributing guidelines](/CONTRIBUTING.md).
+
 ## Badges
 
 Feel free to use it in your own projects: