Replace latest-pkg with latest-build in common commands and
documentation. References to latest-pkg are removed where
latest-build is also present. Also, command description for
latest-build is updated to match the current one.
The HOWTO documentation had a couple "TBD" sections for reporting bugs
or getting involved.
We already say how get involved in the first paragraph of the
documentation, so we do not need these "under construction" sections.