Document that Write Caching must be disabled to avoid possible database corruption

Suggestion that we document a recommendation that Windows Write Caching be disabled on machines using Derby.

The following article warns about Write Caching on Windows as a possbile source of database corruption:
http://support.microsoft.com/kb/281672
It is possible that this could be the cause of some unexplained Derby corruptions identified after power failure of other system interupt.

Links explaining how to disable Write Caching:
Win 2K: http://support.microsoft.com/kb/259716
Win 2008: http://support.microsoft.com/kb/324805

From the Windows 2008 article:
With some third-party programs, disk write caching has to be turned on or off. Additionally, turning disk write caching on may increase operating system performance; however, it may also result in the loss of information if a power failure, equipment failure, or software failure occurs. This article describes how to turn disk write caching on or off.