docs: document python version used for compilation

The drm/msm driver had adopted using Python3 script to generate register
header files instead of shipping pre-generated header files. Document
the minimal Python version supported by the script.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240509-python-version-v1-1-a7dda3a95b5f@linaro.org

Documentation/process/changes.rst

@@ -63,6 +63,7 @@ cpio                   any              cpio --version
 GNU tar                1.28             tar --version
 gtags (optional)       6.6.5            gtags --version
 mkimage (optional)     2017.01          mkimage --version
+Python (optional)      3.5.x            python3 --version
 ====================== ===============  ========================================
 
 .. [#f1] Sphinx is needed only to build the Kernel documentation