Document limitations of examples shipped with this library (#95)

* Document limitations of examples shipped with this library

* Fixing typo.

* Update README.md

Co-authored-by: Pavel Kirienko <pavel.kirienko@gmail.com>

Co-authored-by: Pavel Kirienko <pavel.kirienko@gmail.com>

README.md

@@ -24,6 +24,10 @@ This library works for
 * [UAVCAN-ToF-Distance-Sensor-Node](https://github.com/107-systems/UAVCAN-ToF-Distance-Sensor-Node): Demo firmware for UAVCAN ToF Distance Sensor Node utilizing 107-Arduino-UAVCAN.
 
 ### Example
+**Note**: Please be advised that the [examples](https://github.com/107-systems/107-Arduino-UAVCAN/tree/master/examples) shipped with this library are to be considered minimal examples to get you started working with [UAVCAN](https://uavcan.org/).
+They are known to violate section **2.1.2.2 Regulation** of the UAVCAN Specification due to their reliance on hard-coded port identifiers.
+A compliant implementation would instead provide configurable port-IDs and support the Register Interface (section **5.3 Application-layer functions**).
+Fully compliant examples that implement reconfigurable port-IDs are shipped separately; e.g., [UAVCAN-GNSS-Node](https://github.com/107-systems/UAVCAN-GNSS-Node).
 ```C++
 #include <ArduinoUAVCAN.h>
 /* ... */