Update index.html to reflect new FS Installer stats.

Just the file size and md5 sum are updated here.
This will not be submitted until after:
(1) Sreeniva verifies that the new installer installs the proper version of the
    adaptor-fs-4.0.3-withlib.jar file.
(2) The fs-install-4.0.3.exe executable at
    https://github.com/googlegsa/filesystem/releases/tag/v4.0.3
    is updated to the new installer (which PJ told me would require Siyu's
    action).

Once (1) and (2) are done, I will "git push" this to update the top-level page.