RFR: 8354872: Clarify java.lang.Process resource cleanup

[Roger Riggs]

Improve the documentation of Process use of system resources.

Describe the implementation closing streams when no longer referenced.
Clarify the interactions between inputStream and inputReader and errorStream and errorReader.
Add advice and example using try-with-resources to open and close streams.
Recommend closing streams when no longer in use.

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Commit messages:
 - 8354872: Clarify java.lang.Process resource cleanup

Changes: https://git.openjdk.org/jdk/pull/25884/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25884&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354872
  Stats: 151 lines in 2 files changed: 71 ins; 3 del; 77 mod
  Patch: https://git.openjdk.org/jdk/pull/25884.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25884/head:pull/25884

PR: https://git.openjdk.org/jdk/pull/25884