docs(samples): add default-value sample

[FrodoTheTrue]

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Fixes #<issue_number_goes_here> 🦕

[snippet-bot]

Here is the summary of changes.

You are about to add 6 region tags.

• samples/defaultValues.js:23, tag compute_instances_verify_default_value
• samples/defaultValues.js:39, tag compute_usage_report_set
• samples/defaultValues.js:45, tag compute_instances_verify_default_value
• samples/defaultValues.js:76, tag compute_usage_report_get
• samples/defaultValues.js:81, tag compute_instances_verify_default_value
• samples/defaultValues.js:115, tag compute_usage_report_disable

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[rsamborski]

Please move before the return