gdesktopappinfo: Note that search results are not filtered
Mention in the documentation that (presumably for performance reasons)
the search results from g_desktop_app_info_search()
are not filtered
by executable presence or hidden attribute.
Perhaps they should be in future, but for now we should at least document it.
Spotted by Will Thompson.
Signed-off-by: Philip Withnall withnall@endlessm.com