Update contribution guidelines

Author: pavel-github

.github/CONTRIBUTING.md

@@ -7,87 +7,33 @@ At the same time, reading the contributing guidelines will give you a better ide
 meaningful issues that will be more easily be parsed, considered, and resolved. A big win for
 everyone involved!
 
+## Developing the Driver
 
-## Table of Contents
+If you wish to work on the driver, you'll first need [Go](http://www.golang.org) installed on your machine.
 
-A high level overview of our contributing guidelines.
+*Note:* This project uses [Go Modules](https://blog.golang.org/using-go-modules) making it safe to work with it outside
+of your existing [GOPATH](http://golang.org/doc/code.html#GOPATH). The instructions that follow assume a directory in your
+home directory outside of the standard GOPATH (i.e `$HOME/development/docker-machine-driver-cloudsigma/`).
 
-- [Contributing Code](#contributing-code)
-  - [Setting Up Your Development Environment](#setting-up-your-development-environment)
-  - [Build Tasks](#build-tasks)
-  - [Testing and Building](#testing-and-building)
+Clone repository to: `$HOME/development/docker-machine-driver-cloudsigma/`
 
-Don't fret, it's not as daunting as the table of contents makes it out to be!
-
-
-## Contributing Code
-
-These guidelines will help you get your Pull Request into shape so that a code review can start
-as soon as possible.
-
-### Setting Up Your Development Environment
-
-Fork, then clone the `https://github.com/cloudsigma/docker-machine-driver-cloudsigma` repo into
-*$GOPATH/src/github.com/cloudsigma/docker-machine-driver-cloudsigma*.
-This it important because of golang import path!
-
-```bash
-$ mkdir -p $GOPATH/src/github.com/cloudsigma/docker-machine-driver-cloudsigma
-$ cd $GOPATH/src/github.com/cloudsigma/docker-machine-driver-cloudsigma
-$ git clone https://github.com/cloudsigma/docker-machine-driver-cloudsigma .
-# Change remote name from 'origin' to 'upstream'
-$ git remote rename origin upstream
-# Add remote with name 'origin' from your forked repo
-$ git remote add origin git@github.com:<YOUR-GITHUB-USERNAME>/docker-machine-driver-cloudsigma.git
-# Change remote for master branch
-$ git config branch.master.remote origin
-```
-
-Now you can keep your forked repository up-to-date with the upstream repository with `git fetch upstream`
-and push to your repository with `git push`. See [GitHub Help](https://help.github.com/articles/syncing-a-fork/)
-for more details.
-
-The project uses [Mage](https://magefile.org/) as build tool instead of make, so if you start working
- with our project, then **first install mage**:
-
-```bash
-$ go get -u github.com/magefile/mage
+```sh
+$ mkdir -p $HOME/development; cd $HOME/development
+$ git clone git@github.com:cloudsigma/docker-machine-driver-cloudsigma.git
+...
 ```
 
-Please note that minimum version for building the CloudSigma driver is **Go 1.9 or higher**.
-
-### Build Tasks
-
-The project has predefined the following tasks:
-
-```
-build      Build binary for default local system's operating system and architecture.
-check      Run all checks and tests.
-clean      Delete the build directory.
-fmt        Run gofmt linter.
-release    Build release binaries for all supported versions.
-test       Run all tests.
-vendor     Install all dependencies into vendor directory.
-vet        Run go vet linter.
-```
-
-Task dependencies can be seen on the picture below.
-![build-tasks](build_tasks.png)
-
-E.g. if you run `mage build`, then following tasks will be executed: `fmt -> vendor -> vet -> test -> build`.
-Any customizations of the build process can be done in [Magefile.go](../Magefile.go).
-
-### Testing and Building
-
-To ensure that your changes will not break other functionality, please run the `check` task and
-build process before submitting your Pull Request. You can do it, just run:
+Enter the driver directory and run `make tools`. This will install the needed tools for the driver.
 
-```bash
-$ mage check
+```sh
+$ make tools
 ```
 
-If you want to build docker driver binary file for testing purpose, just run:
+To compile the driver, run `make build`. This will build the driver and put the provider binary in the `build` directory.
 
-```bash
-$ mage build
+```sh
+$ make build
+...
+$ build/docker-machine-driver-cloudsigma
+...
 ```