Windows: ReleaseNotes updates

explicitly list WinRT as unsupported.

Mention KFW 4.0.

Update Reparse Point text.

Update JPSoftware Take Command references.

Update UNC path processing text.  Reference PowerShell 3.0 and Cygwin.

Change-Id: Ib3d4d33173cf4808792c92737eb88a909d7d176b
Reviewed-on: http://gerrit.openafs.org/9589
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>