desktop-entry-spec: %i is allowed to be a part of an larger argument despite being expanded as two arguments

%i Exec field code description:

The Icon key of the desktop entry expanded as two arguments, first --icon and then the value of the Icon key. Should not expand to any arguments if the Icon key is empty or missing.

It wouldn't make much sense to have something like Exec=foo --bar=%i.

"The %F and %U field codes may only be used as an argument on their own" should probably mention %i as well.