[tei-council] Preface updated

[Syd Bauman]

Another thought.

   With this version, the Guidelines also enter a new stage in their
   development as a community-maintained open source project: it is
   the first version to have benefited from the close overview and
   oversight of an elected TEI Technical Council.

Do you intend "community-maintained" to be synonymous with Council
oversight? 

Either way, this implies that all three (community-maintained, open
source, and Council oversight) are all at least very tightly
intertwined if not one and the same. But being open source has
nothing to do with having Council oversight. The TEI-C could have
chosen to develop P5 in complete secrecy with only Council members
and editors able to see the source. Adding a comma, changing colon to
semicolon, and inserting "furthermore" yields:

   With this version, the Guidelines also enter a new stage in their
   development as a community-maintained, open source project;
   furthermore, it is the first version to have benefited from the
   close overview and oversight of an elected TEI Technical Council.

We may also wish to drop "community-maintained". It may imply more
openness than P5 ever enjoyed or had to suffer.