Broken link in FAQ
Specifically the following :-
My macOS system doesn’t let me open GIMP. What do I do? We haven’t yet joined the Apple Developer Program, so the DMG files we provide are unsigned, hence the “unidentified developer” warning. Please follow the procedure described in the Apple’s knowledge base.
https://support.apple.com/kb/PH21769 - broken link. Incidentally the phrasing should be changed to "described in Apple's Knowledge Base" as the word "the" is superfluous in this context.