docs: update s3 repository cache authentication info (#27820)

Co-authored-by: Rhys Arkins <rhys@arkins.net>

docs/usage/self-hosted-configuration.md

@@ -918,17 +918,9 @@ JSON files will be stored inside the `cacheDir` beside the existing file-based p
 }
 ```
 
-<!-- prettier-ignore -->
-!!! note
-    [IAM is supported](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/loading-node-credentials-iam.html) when running Renovate within an EC2 instance in an ECS cluster. In this case, no extra environment variables are required.
-    Otherwise, the following environment variables should be set for the S3 client to work.
-
-```
-    AWS_ACCESS_KEY_ID
-    AWS_SECRET_ACCESS_KEY
-    AWS_SESSION_TOKEN
-    AWS_REGION
-```
+Renovate uses the [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/sdk-for-javascript/v3/developer-guide/welcome.html) to connect to the S3 instance.
+Therefore, Renovate supports all the authentication methods supported by the AWS SDK.
+Read more about the default credential provider chain for AWS SDK for JavaScript V3 [here](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/Package/-aws-sdk-credential-providers/#fromnodeproviderchain).
 
 <!-- prettier-ignore -->
 !!! tip