Minor formatting tweak in release notes.
Empty command-line Holmake only builds first target in Holmakefile.

If there is no Holmakefile, or if there is a Holmakefile with no
targets, then the old behaviour of attempting to build everything
possible happens.

Documented in release notes and DESCRIPTION.

Many of the distribution's Holmakefiles were harmed in the creation of
this commit, but, for the reasons given in the release notes, I don't
think this should happen that often for typical user developments.

Closes #175