Update README.md

Author: nksft

README.md

@@ -1,2 +1,32 @@
 # graylog2-plugin-exec
 An alarm callback plugin for executing a script on Graylog2's server.
+
+## Installation
+
+[Download the plugin](https://github.com/nksft/graylog2-plugin-exec/releases)
+and place the `.jar` file in your Graylog plugin directory. The plugin directory
+is the `plugins/` folder relative from your `graylog-server` directory by default
+and can be configured in your `graylog.conf` file.
+
+Restart `graylog-server` and you are done.
+
+## Usage
+
+Create a "Execute Command Alarm Callback" on the "Manage alerts" page of your stream.
+Enter the requested configuration and save.
+Make sure you also configured alert conditions for the stream so that the alerts are actually triggered.
+
+## Example
+
+For calling the script /root/script.php and passing it a parameter just fill the box like this:
+php /root/script.php param1
+
+## Build
+
+This project is using Maven and requires Java 7 or higher.
+
+You can build a plugin (JAR) with `mvn package`.
+
+## Copyright
+
+Copyright (c) 2016 Ahmad Niksefat. See LICENSE for further details.