Yeah, so long as its clear that this relates to the operating system and particular hardware keyboards thats fine.
Note, I am being totally selfish here, I don't want to be fielding complaints that some binding doesn't work on particular keyboards or systems ;-)
Maybe something like "Shortcuts in this section are _not_ part of Geany but provided by some systems and may be useful in Geany. Some of these may depend on particular keyboard layouts and may not be available on others." as the first line of the new section.