Probably would be best for all people resigning to do it in the Swearing in thread. I recall tyriong or someone having a bill on this but even in the absence of such, it would make things easiest if people just default did it in there.
Well, I can't find it on the wiki, but posting in the swearing in thread would suffice I'm sure. It was just intended to ensure that we knew who's resigned and who's not.
I couldn't remember what exactly it contained or not, but any form of clarification is better than none.