RFR: 8255758: JEP 380 spec clarifications

[Michael McMahon]

Minor spec changes from spec approved in initial CSR

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Commit messages:
 - update to net-properties.html
 - 8255758: JEP 380 spec clarifications

Changes: https://git.openjdk.java.net/jdk/pull/1021/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1021&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255758
  Stats: 70 lines in 3 files changed: 66 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1021.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1021/head:pull/1021

PR: https://git.openjdk.java.net/jdk/pull/1021