Add some guidance to prevent parallel encryption

[wussler]

Addresses #2

[wussler]

Seems like !222 is not getting into the C-R. I would therefore propose to add it to this document and in this PR

WDYT @falko-strenzke, @fluppe2, and @TJ-91?

[TJ-91]

Perhaps it's worth waiting for rechartering and see if it fits better somewhere else (but I'm not completely opposed). My thoughts:

a) while it's relevant for PQC, it's also relevant for OpenPGP in general. b) concentrating on strictly necessary features for PQC might improve the chances of success / reach consensus more easily.

[fluppe2]

The !222 feels more like a general feature request and I'm kind of opposed to blur the line between general stuff and the pqc extension that we are defining.

[wussler]

Sure, but then would it have to be a standalone RFC?

[fluppe2]

I dunno, in my personal opinion that would depend on the general future structure of OpenPGP if it stays a monolithic block or some potential features can be and are discussed as extensions.

[falko-strenzke]

I would also favour to restrict our draft to the PQC-specific features and thus not to address the extension from !222.

[wussler]

Good for me, I'll propose this in the rechartering as a standalone topic looking for a friend.

[wussler]

This PR is supposed to be discussed after adoption, to understand what kind of guidance (if any) is due here

[wussler]

Superseded by #120