RFR: 8287889: (fs) Files.copy description of REPLACE_EXISTING is hard to read

[Brian Burkhalter]

Clarify the descriptions of the use of `java.nio.file.StandardCopyOption.REPLACE_EXISTING` in the `copy(Path,Path)` and `move(Path,Path)` methods of `java.nio.file.Files`. This supersedes https://github.com/openjdk/jdk/pull/9142.

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Commit messages:
 - 8287889: (fs) Files.copy description of REPLACE_EXISTING is hard to read

Changes: https://git.openjdk.org/jdk19/pull/16/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk19&pr=16&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8287889
  Stats: 8 lines in 1 file changed: 0 ins; 2 del; 6 mod
  Patch: https://git.openjdk.org/jdk19/pull/16.diff
  Fetch: git fetch https://git.openjdk.org/jdk19 pull/16/head:pull/16

PR: https://git.openjdk.org/jdk19/pull/16