Minor update to "Joining the LibreOffice Documentation Team"

I have just uploaded an update to the document "Joining the LibreOffice
Documentation Team" (intro-libo-docs-team.odt) in the Docs > Resources
space. All I did was update the email addresses for the mailing list.
I'd hoped to do some more with the content of that chapter, but it's not
going to happen soon (no time), but I didn't want to lead any newcomers
astray with an email address that didn't work.

BTW, I have suggested to the members of the ODFAuthors group (who work
on OOo user guides) that they might help out on LibreOffice docs,
especially until the transition to Apache OpenOffice.org settles down.
Several members are here already, but I hope some of the others will
come along too. Also we get a lot of enquiries from interested people,
some of whom would be a definite asset here as well as on OOo docs.

--Jean