Release Notes update

[John J. McDonough]

I have just pushed a couple of small changes in Release Notes.

The first, BZ#588953, adds a new section, a couple of paragraphs.  Users
of varnish are required to make manual changes to their configuration
file.

The second, BZ#590492, is especially annoying.  There was a stray period
inside a couple of links which broke the link.  Although there is no new
language at all, I think it may poison as many as three strings (or as
few as none).

Thanks
--McD