Update README

Author: fd0

README.md

@@ -1,23 +1,57 @@
 [![Build Status](https://travis-ci.org/fd0/grobi.svg?branch=master)](https://travis-ci.org/fd0/grobi)
 
 # grobi
+
 Watch for changes in outputs for the i3 window manager and react accordingly
 
-# Requirements
+# Installation
+
+Grobi requires Go version 1.4 or newer. To build grobi, run the following command:
 
-Grobi requires Go version 1.4 or newer and the build tool [gb](https://getgb.io). The latter can be installed by running the following command:
 ```shell
-$ go get github.com/constabulary/gb/...
+$ go run build.go
 ```
 
-# Installation
+Afterwards please find a binary of grobi in the current directory:
+```
+$ ./grobi --help
+Usage:
+  grobi [OPTIONS] <command>
+
+Application Options:
+  -v, --verbose   Be verbose (false)
+  -C, --config=   Read config from this file
+  -n, --dry-run   Only print what commands would be executed without actually runnig them
+  -i, --interval= Number of seconds between polls, set to zero to disable polling (5)
+  -p, --pause=    Number of seconds to pause after a change was executed (2)
+
+Help Options:
+  -h, --help      Show this help message
+
+Available commands:
+  apply    apply a rule
+  update   update outputs
+  version  display version
+  watch    watch for changes
+```
+
+# Development
+
+Grobi is developed using the build tool [gb](https://getgb.io). It can be installed by running the following command:
 
-Get all dependencies:
 ```shell
-$ gb vendor restore
+$ go get github.com/constabulary/gb/...
 ```
 
-Compile the program:
+The program can be compiled using `gb` as follows:
+
 ```shell
 $ gb build
 ```
+
+# Compatibility
+
+Grobi follows [Semantic Versioning](http://semver.org) to clearly define which
+versions are compatible. The configuration file and command-line parameters and
+user-interface are considered the "Public API" in the sense of Semantic
+Versioning.