added a description of the config file to the README

README.md

@@ -15,6 +15,32 @@ will be ask if they want to add a node to their blocklist or not.
 The entries of your own servers blocklist will always gain enough trust
 so that they are added on the final blocklist again.
 
+## Config file
+
+To use the script you have to create a config file. The structure of the
+file is the following
+
+```
+[soc1.example.com]
+trust = 40
+
+[soc2.example.com]
+trust = 50
+
+[soc3.example.com]
+trust = 50
+
+[soc4.example.com]
+trust = 90
+```
+
+it assignes _trust_ values to nodes in the network. The node domain names
+are given in the `[]`. These are the nodes that the script will collect
+the server blocklists from.
+
+Trust levels can be negative. Once their summed value does reach a value of
+100 the blocklist entry is trusted automatically without user interaction.
+
 ## Author
 
 * Tobias Diekershoff <tobias(dot)diekershoff(att)gmx(dot)net>