RFR: 8222363 Update ServerSocket.isBound spec to reflect implementation after close

[Michael McMahon]

Could I get the following trivial doc change reviewed please?

Bug report: https://bugs.openjdk.java.net/browse/JDK-8222363

Webrev: http://cr.openjdk.java.net/~michaelm/8222363/webrev.1/index.html

CSR:  https://bugs.openjdk.java.net/browse/JDK-8229978

Thanks,
Michael.