Warn about security risks

Related to #100

README.md

@@ -25,6 +25,9 @@ Electric charge points using the following OCPP versions are supported:
 * OCPP1.6S
 * OCPP1.6J
 
+⚠️ Currently, Steve doesn't support [the OCPP-1.6 security whitepaper](https://openchargealliance.org/wp-content/uploads/2023/11/OCPP-1.6-security-whitepaper-edition-3-2.zip) yet (see [#100](https://github.com/steve-community/steve/issues/100)) and anyone can send events to a public steve instance once the chargebox id is known.
+Please, don't expose a Steve instance without knowing that risk.
+
 For Charging Station compatibility please check:
 https://github.com/steve-community/steve/wiki/Charging-Station-Compatibility