RFR: 8331207: Misleading example in DateFormat#parse docs

[Justin Lu]

Correct a misleading example in the DateFormat parse documentation. 

Common usage is to use a factory instance. The original example provided assumes a pattern provided by a COMPAT factory instance, and does not work with a CLDR instance. 

The example should be updated to use a pattern provided by a CLDR instance, and also explicitly list this pattern for better clarification.

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Commit messages:
 - init

Changes: https://git.openjdk.org/jdk/pull/18983/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18983&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331207
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18983.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18983/head:pull/18983

PR: https://git.openjdk.org/jdk/pull/18983