Add a description

README.md

@@ -1,5 +1,17 @@
 # ngsi-proxy
 
+The [Orion Context Broker](https://github.com/telefonicaid/fiware-orion) is a
+great piece of software for managing context information. Using the RESTful API
+provided from a web browser is easy and can also be simplified by the use of
+some library (e.g. [ngsijs](https://github.com/conwetlab/ngsijs)). However,
+there is a limitation, Orion uses `POST` request for sending notifications. This
+notification mechanism makes imposible to directly receive them on a web page.
+This NGSI proxy creates a server that is capable of receiving `POST`
+notifications and redirect them to web pages through an
+[Event Source](https://developer.mozilla.org/docs/Web/API/EventSource) endpoint.
+
+## Usage
+
 You can install the latest stable version of the `ngsi-proxy` by issuing the
 followign command:
 
@@ -10,7 +22,7 @@ $ npm install -g ngsi-proxy
 Once installed, you will be able to run the `ngsi-proxy` server by using
 the `ngsi-proxy` command. By default, it will be listening on port 3000.
 
-You can use a process manager (e.g. [`pm2`](http://pm2.keymetrics.io/)) for
+You can use a process manager (e.g. [pm2](http://pm2.keymetrics.io/)) for
 running `ngsi-proxy` in a production environment:
 
 ```