Add security considerations section

[jogu]

HAIP is missing the mandatory (according to https://openid.net/wg/resources/naming-and-contents-of-specifications/ ) security considerations section.

[jogu]

Above PR added a very very basic security considerations section. I think we need to expand on this before going to final.

[Sakurann]

how much do we need to actually expand given that we have pretty extensive security considerations sections in VP and VCI?

[jogu]

I honestly don't know. I guess at a minimum we might want to point to add security considerations in other specs we normatively reference. I kind of suspect there must be some choices made in HAIP that have some security considerations but I can't immediately spot what they are.

[jogu]

We have open PRs that add some extra security considerations (#271, #280). I'm not aware of any other pending suggestions (nor do I have any myself) so I suggest closing this one, marking it as pending-close.