Add example BEP JSON for PatternExpanded event type.
Add example BEP JSON for PatternExpanded event type.

Also fixes the description to indicate that the matched patterns appear
as children to the PatternExpanded event.

PiperOrigin-RevId: 370510215

perezd/bazel,cushon/bazel,perezd/bazel,bazelbuild/bazel,meteorcloudy/bazel,meteorcloudy/bazel,cushon/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,cushon/bazel,meteorcloudy/bazel,twitter-forks/bazel,cushon/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,katre/bazel,bazelbuild/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,bazelbuild/bazel,perezd/bazel,perezd/bazel,katre/bazel,meteorcloudy/bazel,cushon/bazel,perezd/bazel,bazelbuild/bazel,twitter-forks/bazel,meteorcloudy/bazel,katre/bazel,ButterflyNetwork/bazel,cushon/bazel,twitter-forks/bazel,bazelbuild/bazel,perezd/bazel,twitter-forks/bazel,twitter-forks/bazel,katre/bazel,katre/bazel,ButterflyNetwork/bazel,perezd/bazel,katre/bazel,twitter-forks/bazel