docs: Adding Samples for Creating Dual Region Buckets

[sydney-munro]

Fixes #1336 ☕️

If you write sample code, please follow the samples format.

[snippet-bot]

Here is the summary of changes.

You are about to add 1 region tag.

• samples/snippets/src/main/java/com/example/storage/bucket/CreateBucketDualRegion.java:19, tag storage_create_bucket_dual_region

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