Replace doc_auto_cfg with doc_cfg to allow docsrs build to succeed (#4331)

## Motivation and Context
<!--- Why is this change required? What problem does it solve? -->
<!--- If it fixes an open issue, please link to the issue here -->
Our docrs builds started
[failing](https://docs.rs/crate/aws-sdk-dynamodb/1.94.0/builds/2555063)
recently with the error:
```
[INFO] [stderr]  Documenting aws-sdk-dynamodb v1.94.0 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0557]: feature has been removed
[INFO] [stderr]   --> src/lib.rs:21:29
[INFO] [stderr]    |
[INFO] [stderr] 21 | #![cfg_attr(docsrs, feature(doc_auto_cfg))]
[INFO] [stderr]    |                             ^^^^^^^^^^^^ feature has been removed
[INFO] [stderr]    |
[INFO] [stderr]    = note: removed in CURRENT_RUSTC_VERSION; see <rust-lang/rust#138907> for more information
[INFO] [stderr]    = note: merged into `doc_cfg`
[INFO] [stderr] 
[INFO] [stderr] error: Compilation failed, aborting rustdoc
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0557`.
[INFO] [stderr] error: could not document `aws-sdk-dynamodb`
```

The [linked issue](rust-lang/rust#138907) shows
that `doc_auto_cfg` has recently been merged into `doc_cfg`. docsrs
builds with the latest nightly toolchain, so the change has impacted our
doc builds. This PR makes that change in codegen and in all of our
runtime crates.

## Checklist
<!--- If a checkbox below is not applicable, then please DELETE it
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.

----

_By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice._

Author: landonxjames

aws/rust-runtime/aws-config/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "aws-config"
-version = "1.8.7"
+version = "1.8.8"
 authors = [
     "AWS Rust SDK Team <[email protected]>",
     "Russell Cohen <[email protected]>",

aws/rust-runtime/aws-config/src/lib.rs

@@ -4,7 +4,7 @@
  */
 
 /* Automatically managed default lints */
-#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 /* End of automatically managed default lints */
 #![allow(clippy::derive_partial_eq_without_eq)]
 #![warn(

aws/rust-runtime/aws-credential-types/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "aws-credential-types"
-version = "1.2.7"
+version = "1.2.8"
 authors = ["AWS Rust SDK Team <[email protected]>"]
 description = "Types for AWS SDK credentials."
 edition = "2021"

aws/rust-runtime/aws-credential-types/src/lib.rs

@@ -4,7 +4,7 @@
  */
 
 /* Automatically managed default lints */
-#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 /* End of automatically managed default lints */
 //! `aws-credential-types` provides types concerned with AWS SDK credentials including:
 //! * Traits for credentials providers and for credentials caching

aws/rust-runtime/aws-inlineable/src/lib.rs

@@ -4,7 +4,7 @@
  */
 
 /* Automatically managed default lints */
-#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 /* End of automatically managed default lints */
 //! Collection of modules that get conditionally included directly into the code generated
 //! SDK service crates. For example, when generating S3, the `s3_errors` module will get copied

aws/rust-runtime/aws-runtime-api/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "aws-runtime-api"
-version = "1.1.8"
+version = "1.1.9"
 authors = ["AWS Rust SDK Team <[email protected]>"]
 description = "Runtime support code for the AWS SDK. This isn't intended to be used directly."
 edition = "2021"

aws/rust-runtime/aws-runtime-api/src/lib.rs

@@ -4,7 +4,7 @@
  */
 
 /* Automatically managed default lints */
-#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 /* End of automatically managed default lints */
 //! Runtime support code for the AWS SDK. This crate isn't intended to be used directly.
 

aws/rust-runtime/aws-runtime/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "aws-runtime"
-version = "1.5.11"
+version = "1.5.12"
 authors = ["AWS Rust SDK Team <[email protected]>"]
 description = "Runtime support code for the AWS SDK. This crate isn't intended to be used directly."
 edition = "2021"

aws/rust-runtime/aws-runtime/src/lib.rs

@@ -4,7 +4,7 @@
  */
 
 /* Automatically managed default lints */
-#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![cfg_attr(docsrs, feature(doc_cfg))]
 /* End of automatically managed default lints */
 //! Runtime support code for the AWS SDK. This crate isn't intended to be used directly.
 

aws/rust-runtime/aws-sigv4/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "aws-sigv4"
-version = "1.3.4"
+version = "1.3.5"
 authors = ["AWS Rust SDK Team <[email protected]>", "David Barsky <[email protected]>"]
 description = "SigV4 signer for HTTP requests and Event Stream messages."
 edition = "2021"