Minor readme update (#1025)

* readme and BLE update

docs/README.md

@@ -1,4 +1,4 @@
-OpenMQTTGateway project goal is to concentrate in one gateway different technologies, decreasing by the way the number of proprietary gateways needed, and hiding the different technologies singularity behind a simple & wide spread communication protocol; [MQTT](http://mqtt.org/).
+OpenMQTTGateway project goal is to concentrate in one firmware different technologies and protocols, decreasing by the way the number of physical bridges needed, and hiding the different technologies singularity behind a simple & wide spread communication protocol; [MQTT](http://mqtt.org/).
 
 ![Overview](./img/OpenMQTTGateway.png)
 

docs/use/ble.md

@@ -1,4 +1,10 @@
 # BLE gateway
+
+::: warning
+We strongly encourage the use of a white-list (see below) so as to collect data from your devices only and not from other MAC addresses.
+By default the gateway scans the advertizing BLE devices nearby with their MAC addresses. Depending on your country, it may be illegal to monitor networks for MAC addresses, especially on networks that you do not own. Please check your country's laws (for US Section 18 U.S. Code § 2511) - [discussion here](https://github.com/schollz/howmanypeoplearearound/issues/4).
+:::
+
 ## Receiving signals from BLE beacon devices for Presence detection
 
 Subscribe to all the messages with mosquitto or open your MQTT client software: