journal: unify template name for "nodes" (BC)
This is a part of the name unification.
https://www.mercurial-scm.org/wiki/GenericTemplatingPlan#Dictionary
.. bc::
``{oldhashes}`` and ``{newhashes}`` in journal template are renamed to
``{oldnodes}`` and ``{newnodes}`` respectively.
#require docutils gettext
$ $TESTDIR/check-gendoc pt_BR
checking for parse errors