Update manpages for 0.19.1 release

Summary: See title. Depends on D2669

Test Plan: Read it.

Reviewers: deadalnix, Fabien, Mengerian, #bitcoin_abc

Reviewed By: Fabien, Mengerian, #bitcoin_abc

Subscribers: teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2670