git: openjdk/amber-docs: Fixing syntax in example (#20)

[duke]

Changeset: 33c5b894
Author:    David Alayachew <davidalayachew at gmail.com>
Committer: GitHub <noreply at github.com>
Date:      2023-07-11 04:19:35 +0000
URL:       https://git.openjdk.org/amber-docs/commit/33c5b894f224491e1c998f9bd6521b6395fca292

Fixing syntax in example (#20)

Missing a parentheses

! site/design-notes/patterns/pattern-match-object-model.md