[amber-docs] RFR: Update pattern-match-object-model.md

[Ram Anvesh Reddy]

Correct collection literal deconstruction pattern example syntax ( , was used instead of : )

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Commit messages:
 - Update pattern-match-object-model.md

Changes: https://git.openjdk.org/amber-docs/pull/24/files
  Webrev: https://webrevs.openjdk.org/?repo=amber-docs&pr=24&range=00
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/amber-docs/pull/24.diff
  Fetch: git fetch https://git.openjdk.org/amber-docs.git pull/24/head:pull/24

PR: https://git.openjdk.org/amber-docs/pull/24