Updating the manpages is a semi-manual process:
(all paths below relative to top of git tree):

1) make changes to the .rst files in doc/man.
2) if adding or removing pages, update man/CMakeLists.txt
3) use admin/build-doc to build the doc tree into build-doc/output
4) copy changed manpage files from build-doc/output/man to man/
5) commit both doc/man .rst changes and man/ changes