feat(DRIVERS-2983): use custom aws configuration

source/auth/auth.md

@@ -987,6 +987,22 @@ those credentials will be used by default if AWS auth environment variables are
 application. Alternatively, you can create an AWS profile specifically for your MongoDB credentials and set the
 `AWS_PROFILE` environment variable to that profile name."
 
+##### Custom Credential Providers
+
+Drivers that choose you use the AWS SDK to fetch credentials MAY also allow users to provide a custom credential provider
+as an option to the `MongoClient`. The interface for the option provided depends on the individual language SDK and
+drivers MUST consult AWS SDK documentation to determine that format when implementing. The name of the option MUST be
+`AWS_CREDENTIAL_PROVIDER` and be part of the authentication mechanism properties options that can be provided to the
+client.
+
+Drivers that implement this MAY choose to implement the following scenarios when applicable in their labguage's SDK:
+
+1. The default SDK credential provider.
+2. A custom credential provider chain.
+3. A single credential provider of any available SDK options provided by the SDK.
+
+##### Credential Fetching Order
+
 The order in which Drivers MUST search for credentials is:
 
 1. The URI
@@ -1306,6 +1322,10 @@ in the MONGODB-OIDC specification, including sections or blocks that specificall
         check MUST be performed after SRV record resolution, if applicable. This property is only required for drivers
         that support the [Human Authentication Flow](#human-authentication-flow).
 
+    - AWS_CREDENTIAL_PROVIDER
+
+        A function or object from the AWS SDK that can be used to return AWS credentials.
+
 <span id="built-in-provider-integrations"/>
 
 #### Built-in OIDC Environment Integrations