Per CSR feedback:

- Add this to ValueBased.html: "Identity-related behavior of value-based classes may change in a future release."

- Modify the boilerplate in linking value-based classes to say:

 * <p>This is a <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>
 * class; programmers should treat instances that are
 * {@linkplain #equals(Object) equal} as interchangeable and should not
 * use instances for synchronization, or unpredictable behavior may
 * occur. For example, in a future release, synchronization may fail.