docs: update README.md

README.md

@@ -1,3 +1,34 @@
-# Basic Code Example using Gradle
+# QRBill generator API
 
-This minimal code example shows how to generate a QR bill. It uses the Gradle build system.
+Available at http://clic.epfl.ch/qrbill-generator.
+
+### `POST
+
+#### Request Body
+
+```json
+{
+  "account": "CH2304835177498341002",
+  "amount": 10,
+  "currency": "CHF",
+  "message": "Custom message",
+  "creditor": {
+    "name": "CLIC",
+    "street": "Station 14, EPFL",
+    "houseNo": "",
+    "postalCode": "1015",
+    "town": "Lausanne",
+    "countryCode": "CH"
+  }
+}
+```
+
+#### Response body
+
+Returns the QR Bill as a SVG image.
+
+#### Example with cURL
+
+```
+curl -X POST https://clic.epfl.ch/qrbill-generator/ -d '{"account":"CH2304835177498341002","amount":10,"currency":"CHF", "message": "Souper de Faculté - Ludovic Mermod","creditor":{"name":"CLIC","street":"Station 14, EPFL","houseNo":"","postalCode":"1015","town":"Lausanne", "countryCode": "CH"}}'
+```