Add a new `make install-all` command that will perform all `make
install` actions along with generating the manpages. The `manpages`
command is then removed from the existing `make install` command. The
docker build is then updated to use the new `make install-all` command.
This is done because some users running `make install` may be doing so
in environments where they do not have write access to the directory
where the man pages need to be written to.
As usual, we keep with the last two Go versions, which means the last
year of Go release (they release every 6 months or so).
This change means we can now use the type params (generics) in the
project!
To finally end the discussion what Dockerfile should be used for what
and whether we should build from local source or check out from git, we
place both Dockerfiles next to each other and explicitly document their
purpose.
