Add includes key in library.properties

Author: sandeepmistry

library.properties

@@ -7,3 +7,4 @@ paragraph=This library can be used for HTTP (GET, POST, PUT, DELETE) requests to
 category=Communication
 url=https://github.com/arduino-libraries/ArduinoHttpClient
 architectures=*
+includes=ArduinoHttpClient.h