Since https://github.com/theupdateframework/tuf/pull/781 we
only provide limited protection against slow retrieval attacks.
So far this has only been discussed in above issue and hinted at
by a disabled test and a code comment in that test.
This change adds a corresponding disclaimer to a more prominent
place, i.e. the list of attacks in SECURITY.md.
Signed-off-by: Lukas Puehringer <lukas.puehringer@nyu.edu>
Co-Authored-By: Trishank K Kuppusamy <33133073+trishankatdatadog@users.noreply.github.com>