OpenPGP is a new feature and it should be documented. Also X.509.
And digital signatures should be documented and updated, because it's general now, without details which perplex users and make new bugs.
Also, Related Topics: English Wiki page on digital signatures points to https://wiki.documentfoundation.org/How_to_use_digital_Signatures which only has the link to https://wiki.openoffice.org/wiki/How_to_use_digital_Signatures.
It should also be explained how LO finds certificate manager on different platforms and what a user can do if s/he gets a message "Could not find any certificate manager".
Olivier Hallot committed a patch related to this issue.
It has been pushed to "master":
tdf#116078 OpenPGP encryption
A polite ping to Olivier Hallot:
Is this bug fixed? if so, could you please close it as RESOLVED FIXED ? Otherwise, Could you please explain what's missing?