Add "Building" section to README.md

Author: monochromata

README.md

@@ -9,6 +9,47 @@ Create Docker machines on [Hetzner Cloud](https://docs.hetzner.cloud/).
 You need to create a project-sepcific access token under `Access` > `API Tokens` in the project control panel
 and pass that to `docker-machine create` with the `--hetzner-api-token` option.
 
+## Building
+
+Use an up-to-date version of [go](https://golang.org/dl)
+
+### For use
+
+To use the driver, you can download the sources and build it locally:
+
+```
+# Tell GO where to find sources and where to put binaries (see also https://github.com/golang/go/wiki/SettingGOPATH)
+export GOPATH="$(pwd)"
+export GOBIN=$GOPATH/bin
+# Build the binary
+go get github.com/jonasprogrammer/docker-machine-driver-hetzner
+# Make the binary accessible to docker-machine
+export PATH="$PATH:$GOBIN"
+# Make docker-machine output help including hetzner-specific options
+docker-machine create --driver hetzner
+```
+
+### For development
+
+To compile the local sources, do the following:
+
+```
+# Check out sources
+git clone https://github.com/JonasProgrammer/docker-machine-driver-hetzner.git
+# Tell GO where to find sources and where to put binaries (see also https://github.com/golang/go/wiki/SettingGOPATH)
+export GOPATH="$(pwd)"
+export GOBIN=$GOPATH/bin
+# Build the binary
+go get
+# Make the binary accessible to docker-machine
+export PATH="$PATH:$GOBIN"
+# Make docker-machine output help including hetzner-specific options
+docker-machine create --driver hetzner
+```
+TODO: restructure code
+TODO: Go version
+TODO: set $GOPATH
+
 ## Usage
 
     $ docker-machine create --driver hetzner --hetzner-api-token=QJhoRT38JfAUO037PWJ5Zt9iAABIxdxdh4gPqNkUGKIrUMd6I3cPIsfKozI513sy some-machine