JDK-6962494: Update documentation on Executable.getParameterAnnotations()

[Eric McCorkle]

Hello,

Please review this patch which updates the javadoc comments for
java.lang.reflect.Executable.getParameterAnnotations().  The patch
corrects the javadocs to describe the actual behavior of this method.
It also refers users to the new java.lang.reflect.Parameter API.

See comments on the bug report for more details:
https://bugs.openjdk.java.net/browse/JDK-6962494

The webrev is here:
http://cr.openjdk.java.net/~emc/6962494/

This is also under review in crucible.  The review link is here:
http://sthinfra10.se.oracle.com:8060/cru/CR-JDK8TL-171

Thanks,
Eric