Missing example .rst files for some SNS commands

### Describe the issue

Hello. This is my first contribution to the AWS CLI project, so please let me know if there is anything I may be missing.

Under awscli/examples/sns, there are .rst files that document examples for SNS commands. However, when comparing this directory with the SNS commands listed in the AWS CLI Command Reference, I found that there are no corresponding .rst example files for the following commands.

Could you please let me know whether this is expected, or if additional example files should be added? If action is needed, I would be happy to create the missing .rst files and submit a pull request.

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create-sms-sandbox-phone-number
delete-sms-sandbox-phone-number
get-data-protection-policy
get-sms-sandbox-account-status
list-origination-numbers
list-sms-sandbox-phone-numbers
publish-batch
verify-sms-sandbox-phone-number

### Links

- The directory that contains the .rst files for SNS command examples
- https://github.com/aws/aws-cli/tree/master/awscli/examples/sns
- AWS CLI Command Reference
- https://docs.aws.amazon.com/cli/latest/reference/sns/