improve readme

README.md

@@ -20,3 +20,16 @@ Simplistic server that connect to a Telegram bot, takes messages via *POST*-requ
        --interface INTERFACE    Interface on which to listen (default: localhost)
        --port PORT              Port on which to listen (default: 5000)
        --token-file TOKEN_FILE  File containing the Bot-Token (default: bot.token)
+
+# HTTP Request
+The HTTP request must be a *POST*-request, with *Content-Type: application/json* and a json-field containing the key *"message"* with the value being the message you want to send.
+
+The following locations are supported:
+
+    /send-all   # send a message to all subscribed clients
+
+# Example (curl)
+
+    curl -X POST -H "Content-Type: application/json" --data '{"message":"hallo world"}' localhost:5000/send-all
+
+