doc/Makefile: Don't show Makefile comments in output
The comments makes sense when editing Makefile, but not when watching its
output where it looks too much like error messages.
% no repo
abort: There is no Mercurial repository here (.hg not found)
% create repo
adding a
% basic id usage
cb9a9f314b8b tip
cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b tip
cb9a9f314b8b
cb9a9f314b8b tip
% with options
cb9a9f314b8b tip
0
tip
default
cb9a9f314b8b
cb9a9f314b8b 0 default tip
% with modifications
cb9a9f314b8b+ 0+ default tip
% other local repo
cb9a9f314b8b+ tip
cb9a9f314b8b+ tip
% with remote http repo
cb9a9f314b8b
% remote with tags?
abort: can't query remote revision number, branch, or tags