Merge pull request #20 from kallies/update_readme

Move README to Markdown file and update content

Author: liske

README

@@ -0,0 +1,43 @@
+README for apt-dater-host
+=========================
+
+Setup hosts managed by apt-dater:
+---------------------------------
+
+  You need a SSH server and `sudo` installed. Create a user (`the-user` in this
+  example) which will be used to install updates (using root is NOT recommended).
+
+    useradd the-user
+
+  Modify the sudoers rules, e.g. `/etc/sudoers` or `/etc/sudoers.d/apt-dater-host`:
+
+	Defaults env_reset,env_keep=MAINTAINER
+	the-user ALL=NOPASSWD: /usr/bin/apt-get, /usr/sbin/needrestart
+
+  For non apt-based distributions you need to replace
+  `/usr/bin/apt-get` with the equivalent, e.g. `/usr/bin/yum`.
+
+  You can verify the setup by calling
+
+    sudo -l -U the-user
+
+Additional steps for a manual `apt-dater-host` installation:
+------------------------------------------------------------
+
+  Put `apt-dater-host` on the managed host (folder must be present in `$PATH` of `the-user`).
+
+  Put `apt-dater-host.conf` to `$CFGFILE` (default is `/etc/apt-dater-host.conf`).
+
+At your management server:
+--------------------------
+
+  Create a user on your management server which perform updates on your
+  hosts.
+
+  Generate a SSH keypair:
+
+    ssh-keygen [..] -f ~/.ssh/apt-dater
+
+  Distribute the public key(s) e.g.:
+
+    ssh-copy-id -i ~/.ssh/apt-dater.pub the-user@managed-host