diff --git a/README.md b/README.md
index f87f5c1..ef86708 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,24 @@
-# TODO
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+# tobias_richter.apt_config
+
+[![Build Status](https://travis-ci.org/tobias-richter/ansible-apt-config.svg?branch=master)](https://travis-ci.org/tobias-richter/ansible-apt-config)
+
+This roles configures apt sources, preferences and apt-cacher-ng / proxy for Debian and Ubuntu.
+
+## Requirements
+
+This role requires Ansible 2.7 or higher.
+
+## Role Variables
+
+See [defaults/main.yml](defaults/main.yml) for the documented role variables.
+See also the distribution specific [vars](vars).
+
+
+## Example Playbook
+
+This playbook configures apt together with a proxy server / apt-cacher-ng.
+
+    - hosts: apt_config
+	  roles:
+	    - role: tobias_richter.apt_config
+	      apt_config_apt_cacher_ng: http://apt-cacher-ng.main.corp
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diff --git a/defaults/main.yml b/defaults/main.yml
index 866fd41..9d67ed9 100644
--- a/defaults/main.yml
+++ b/defaults/main.yml
@@ -1,10 +1,15 @@
-# use apt-cacher-ng when defined
+# configure apt-cacher-ng when defined
 # apt_config_apt_cacher_ng:
 
+# Path to sources.list
 apt_config_sources_list_path: /etc/apt/sources.list
 
 # distribution release
 apt_config_distribution_release: "{{ ansible_distribution_release }}"
 
-_apt_config_components_custom: "{{ apt_config_components_custom | default([]) }}"
-apt_config_components: "{{ apt_config_components_default | union(_apt_config_components_custom) }}"
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+# custom componens
+apt_config_components_custom: []
+# e.g.
+# - rpimain
+
+apt_config_components: "{{ apt_config_components_default | union(apt_config_components_custom) }}"
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diff --git a/vars/default.yml b/vars/default.yml
index 9faa770..5f88df3 100644
--- a/vars/default.yml
+++ b/vars/default.yml
@@ -1,3 +1,4 @@
+# default debs to configure
 apt_config_debs:
   - uri: http://ftp.debian.org/debian
     suite: "{{ apt_config_distribution_release }}"
@@ -8,6 +9,7 @@ apt_config_debs:
   - uri: http://ftp.debian.org/debian
     suite: "{{ apt_config_distribution_release }}-backports"
 
+# default components
 apt_config_components_default:
   - main
   - contrib
diff --git a/vars/distribution_Ubuntu.yml b/vars/distribution_Ubuntu.yml
index f0a2487..3c48a10 100644
--- a/vars/distribution_Ubuntu.yml
+++ b/vars/distribution_Ubuntu.yml
@@ -1,3 +1,4 @@
+# Ubuntu debs
 apt_config_debs:
   - uri: http://archive.ubuntu.com/ubuntu
     suite: "{{ apt_config_distribution_release }}"
@@ -8,6 +9,7 @@ apt_config_debs:
   - uri: http://archive.ubuntu.com/ubuntu
     suite: "{{ apt_config_distribution_release }}-backports"
 
+# Default ubuntu components
 apt_config_components_default:
   - main
   - restricted
diff --git a/vars/lsb_id_Raspbian.yml b/vars/lsb_id_Raspbian.yml
index d2eebe9..9069589 100644
--- a/vars/lsb_id_Raspbian.yml
+++ b/vars/lsb_id_Raspbian.yml
@@ -1,9 +1,10 @@
+# Raspbian debs
 apt_config_debs:
   - uri: http://raspbian.raspberrypi.org/raspbian
     suite: "{{ apt_config_distribution_release }}"
 
+# Raspbian components
 apt_config_components_default:
   - main
   - contrib
-  - non-free
-#  - rpimain
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+  - non-free
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