RFR: 8283779: Clarify API documentation of NetworkInterface with respect to configuration changes

[Daniel Fuchs]

Please find here a change that adds a few `@apiNote` and `@implNote` to `NetworkInterface` to clarify user expectation and implementation.

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Commit messages:
 - 8283779

Changes: https://git.openjdk.org/jdk/pull/20822/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20822&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8283779
  Stats: 63 lines in 1 file changed: 59 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/20822.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20822/head:pull/20822

PR: https://git.openjdk.org/jdk/pull/20822