Update man pages for v0.18.7

Summary: As per title

Test Plan:
Read the man. To know how to do so:

man man

Reviewers: #bitcoin_abc, deadalnix, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Subscribers: teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2411