Update README.md

Author: fpistm

examples/Boards/STM32L475VG-DISCOVERY-IOT/WiFi_MQTT_Adafruit.io/README.md

@@ -25,8 +25,8 @@ Install the following libraries using the Arduino IDE: **_Sketch -> Include Libr
    * temp: Stream block
    * hum: Gauge block
 
- A screenshot of the dashboard:
- [[/img/dashboard_adafruit.png|alt="Dashboard Adafruit"]]
+ A screenshot of the dashboard: 
+ [Dashboard Adafruit](/img/dashboard_adafruit.png)
 
   It connects to the Adafruit IO's MQTT server (a.k.a broker) server then:
   * publishes announcement "_Hi, I'm STM32 user!_" to the topic `AIO_USERNAME"/feeds/hello"`