added note about class changes and how to port code forward to v2 of the library

Author: gigapod

README.md

@@ -13,13 +13,20 @@ Arduino Library for the SparkFun Pulsed Coherent Radar Sensor
 ![GitHub issues](https://img.shields.io/github/issues/sparkfun/SparkFun_Qwiic_XM125_Arduino_Library)
 
 
-
 The [SparkFun Pulsed Coherent Radar Sensor - Acconeer XM125 (SEN-24540)](https://www.sparkfun.com/sparkfun-pulsed-coherent-radar-sensor-acconeer-xm125-qwiic.html) brings powerful 60 GHz radar technology to your projects. This sensor isn't limited to surface detection; it can see through walls, cabinets, and even pockets (depending on the material), making it perfect for unique applications. Measure distances with millimeter precision, detect motion, the speed of an object, or even gestures!
 
 The XM125 boasts an impressive range of up to 20 meters, allowing you to create long-range sensing projects. The actual measurable distance is dependent on the object size, shape, dielectric properties, and lens (e.g. water level measurements up to 20 meters with lens utilization, human presence detection up to 7 meters with lens-free utilization). Despite its power, the sensor has remarkably low in power consumption, which is ideal for battery-powered applications. The real magic lies in the sensor's ability to do more than measure distance; the XM125 can differentiate between stationary objects and moving targets using pulsed coherent radar. This means you can sense an object's presence and how fast something is moving!
 
 Looking for the board that matches this library - pick up a [SparkFun Pulsed Coherent Radar Sensor - Acconeer XM125 (Qwiic)](https://www.sparkfun.com/sparkfun-pulsed-coherent-radar-sensor-acconeer-xm125-qwiic.html) at www.sparkfun.com.
 
+> [!NOTE]
+> Version 2.0+ of this library is not compatible with Version 1.0 implementations/use. For Version 2.0, the single class defined by the library, `SparkFunXM125`, was divided into two distinct classes:
+>
+> *  SparkFunXM125Distance - Used when the XM125 is running the ***Distance*** application
+> *  SparkFunXM125Presence - Used when the XM125 is running the ***Presence*** application
+>
+> Moving to use Version 2.0 of the library just requires changing the class name used in your sketch - from `SparkFunXM125` to either `SparkFunXM125Distance` or `SparkFunXM125Presence`
+
 ## Functionality
 
 The SparkFun Pulsed Coherent Radar sensor can run as an I2C client device, or as a standalone development board. This library is used when the sensor is operating as a standalone I2C device.