CON-253: Document bug in numpy on aarch64 (#113)

examples/python/images/README.md

@@ -8,7 +8,7 @@ the most recently received image and display it.
 This example shows how to manipulate a more complex type.
 
 ## Running the example
-This examples requires *Python 3.x* and the packages **matplotlib** and **numpy**:
+This examples requires *Python 3.x* and the packages **matplotlib** and **numpy**[^1]:
 
     $ pip install matplotlib numpy
 
@@ -21,3 +21,6 @@ To run the example, in different shells, run any number of instances of the writ
 installation doesn't have one, you can run `image_reader_file.py` instead, which
 will save the last image into a file called *image.png*.
 
+[^1]: On ARMv8 architectures, version 1.19.5 of numpy is not supported, due to
+[numpy issue 18131](https://github.com/numpy/numpy/issues/18131).
+Version 1.19.4 of numpy has been tested to work on ARMv8 architectures.