Release Note: Clarify the Specification of ReadableByteChannel.read() and Related Methods

The specifications of the `DatagramChannel.receive()`, `FileChannel.read(ByteBuffer,long)`, `ReadableByteChannel.read()`, and `ScatteringByteChannel.read()` methods have been updated in this release to specify that an `IllegalArgumentException` is thrown if (any of) the buffer parameter(s) is read-only. This change merely adjusts the specification to match existing long term behavior.