RFR: JDK-8241995: Clarify InetSocketAddress::toString specification

[Julia Boes]

This change clarifies the InetSocketAddress::toString specification, which was recently updated to reflect an implementation change [1]. The specification is not changed, but it is enhanced with two examples and some more verbiage, as per earlier suggestions on the net-dev mailing list [2][3].

[1] https://bugs.openjdk.java.net/browse/JDK-8225499
[2] https://mail.openjdk.java.net/pipermail/net-dev/2020-April/013776.html
[3] https://mail.openjdk.java.net/pipermail/net-dev/2021-February/015297.html

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Commit messages:
 - clarify method-level javadoc

Changes: https://git.openjdk.java.net/jdk/pull/2357/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2357&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8241995
  Stats: 12 lines in 1 file changed: 7 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2357.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2357/head:pull/2357

PR: https://git.openjdk.java.net/jdk/pull/2357