build-aux: Relax the regexp used to match NEWS sections....A number of packages doesn't really make sense in the name of the section to
be substituted. This change allows using simply '*** new packages' instead of
'*** 1999 new packages', for example, and have the update-NEWS.scm script
update it.
* build-aux/update-NEWS.scm (write-packages-added) <regexp>: Do not care about
leading white space in the name of the section.