[FYI] Revised template message for new committer/PPMC member invitation

[Bertrand Delacretaz <bd...@apache.org>]

Hi Flex PPMC members,

I have added links to
http://www.apache.org/dev/new-committers-guide.html and
http://www.apache.org/licenses/cla-corporate.txt to the invitation
that we send to new committers and PPMC members, see
https://cwiki.apache.org/confluence/display/FLEX/New+committer+or+PMC+member+invitation

I suggest using that template in the future, as it contains (IMO) all
the information that new committers need. So far we've sent the first
3 links only, and probably forgot to send the others later when people
accept the invitation.

-Bertrand