Remove the examples directory (#1351)

This PR removes the
[`examples`](https://github.com/awslabs/aws-sdk-rust/tree/67af42f0f7dcf8410782aed5c4d061d71eb0eab9/examples)
directory from the repository. Going forward, we will direct users to
[aws-doc-sdk-examples](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/rustv1)
in the `README`.

Note: The re-direction will be handled in a subsequent PR. In the
meantime, the example links in the `README` will be temporarily broken
after this PR is merged.

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Author: ysaito1001