docs(README): add migration from 1.x.x to 2.x.x

Signed-off-by: Benjamin Coenen <benjamin.coenen@corp.ovh.com>

README.md

@@ -140,6 +140,31 @@ You can browse the API schemas using the web consoles of the APIs:
 * [Kimsufi Europe](https://eu.api.kimsufi.com/console/)
 * [Kimsufi North-America](https://ca.api.kimsufi.com/console/)
 
+## Migration from 1.x.x to 2.x.x without Proxy support
+
+For example if you use the OVH Europe API, you'll have to check on https://eu.api.ovh.com/console/ the endpoints available for your feature.
+
+In order to have the informations about the bill with id "0123".
++ Before in 1.x.x with Proxy:
+
+```javascript
+ovh.me.bill["0123"].$get(function (err, billInformation) {
+
+});
+```
+
++ Now in 2.x.x with promise:
+
+```javascript
+ovh.requestPromised('GET', '/me/bill/0123') //This route has been found at https://eu.api.ovh.com/console/
+  .then(function (billInformation) {
+
+  })
+  .catch(function (err) {
+
+  });
+```
+
 ## Full documentation and examples
 
 The full documentation is available online: http://ovh.github.io/node-ovh.