doc: fix typo provicer -> provider (#4207)

## Motivation and Context
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To fix a small typo

## Description
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The docs for
https://docs.rs/aws-credential-types/1.2.3/aws_credential_types/struct.CredentialsBuilder.html#method.provider_name


has a typo for the word provider

## Testing
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to -->
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I think this is not applicable since it's a doc change

## Checklist
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rather than leaving it unchecked -->
- [ ] For changes to the smithy-rs codegen or runtime crates, I have
created a changelog entry Markdown file in the `.changelog` directory,
specifying "client," "server," or both in the `applies_to` key.
- [ ] For changes to the AWS SDK, generated SDK code, or SDK runtime
crates, I have created a changelog entry Markdown file in the
`.changelog` directory, specifying "aws-sdk-rust" in the `applies_to`
key.

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Co-authored-by: Landon James <lnj@amazon.com>