Changed file in Installation section where users should look for instructions from release_docs\INSTALL_Windows.txt to release_docs\INSTALL. Fixes HDFFV-8868.

Tested: Doxygen
Description:
    Initial tweaks to align with VOL branch.

Tested on:
    Mac OSX/64 10.9.3 (amazon) w/gcc 4.9
    (h5committest not required, too small)