Bump to 1.6.0 (workspace sync, no functional change). Fix the README
example that called the removed matches()/unlock() API — rewrite to the
real unlock_features()/unlock_bus() contract (+ ld/README).
The unlocker performs the DVD bus-auth that clears the drive's
scrambled-read barrier, letting a protected DVD be read at all. That is
a property of the DVD medium, not of the CSS scheme — the descramble key
is recovered keylessly downstream — so naming it "CSS" conflated the
read-enable with the encryption. Rename the struct to DvdUnlocker, its
registry name to "DVD", and the tests to match. Bump 1.5.2.
Matthew Jackson