Update ADU sample readme about required library beta version

examples/Azure_IoT_Adu_ESP32/readme.md

@@ -88,7 +88,7 @@ Viewing the device twin on the portal, the "tag" section should look similar to
 
     - On the Arduino IDE, go to menu `Sketch`, `Include Library`, `Manage Libraries...`.
     - Search for and install `azure-sdk-for-c`.
-    - **Make sure to install the `1.1.0-beta.1` to use the preview version of the Embedded C SDK.**
+    - **Make sure to install the latest `1.1.0-beta.*` to use the preview version of the Embedded C SDK.**
 
 1. Open the ESPRESSIF ESP32 sample.