[thredds] announce: replace TDS 4.2.4 with 4.2.5

TDS 4.2.5 fixes a few problems with the 4.2.4 release. It is available as the "latest TDS 4.2 release" at the usual place:

http://www.unidata.ucar.edu/projects/THREDDS/tech/TDS.html

If you are using 4.2.4, please use4.2.5instead. If you are using an earlier 
version, please upgrade asap, as our ability to support earlier versions is, 
um, limited.

If you see any problems, please let us know.

Thanks!

John, Ethan, Dennis