Fixed links on qt4cg.org

Hi folks,

At some point, not recently I don’t think, I switched from using
/branch/master to hold the “current” versions of the specifications to
using /specifications.

Unfortunately, I didn’t notice several places where the old links had
persisted. I happened to delete the (now quite stale) versions at
/branch/master yesterday inadvertantly creating a bunch of 404s.

Mea culpa.

I believe I’ve fixed the qt4cg.org home page and the qtspecs README.md
file, but the changes will take a few minutes to percolate through the
intertubes.

Apologies for the inconvenience.

                                        Be seeing you,
                                          norm

--
Norm Tovey-Walsh
Saxonica