Add user guide for SSO provider usage

docs/source/guide/credentials.rst

@@ -232,6 +232,38 @@ This provider can also be configured via environment variables:
 
     These environment variables currently only apply to the assume role with web identity provider and do not apply to the general assume role provider configuration.
 
+AWS Single Sign-On Provider (SSO)
+-----------------------------------
+
+Support for the AWS Single Sign-On (SSO) credential provider was added in 1.14.0.
+
+To begin using the SSO credential provider, start by using the AWS CLI V2 to configure and manage your SSO profiles and login sessions.
+For detailed instructions on the configuration and login process see the `AWS CLI User Guide for SSO <https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-sso.html>`_.
+Once completed you will have one or many profiles in the shared configuration file with the following settings:
+
+.. code-block:: ini
+
+    # In ~/.aws/config
+    [profile my-sso-profile]
+    sso_start_url = https://my-sso-portal.awsapps.com/start
+    sso_region = us-east-1
+    sso_account_id = 123456789011
+    sso_role_name = readOnly
+
+* ``sso_start_url`` - The URL that points to the organization's AWS SSO user portal.
+* ``sso_region`` - The AWS Region that contains the AWS SSO portal host. This is separate from, and can be a different region than the default CLI region parameter.
+* ``sso_account_id`` - The AWS account ID that contains the IAM role that you want to use with this profile.
+* ``sso_role_name`` - The name of the IAM role that defines the user's permissions when using this profile.
+
+You can then specify the profile name via the ``AWS_PROFILE`` environment variable or the ``profile_name`` argument when creating a ``Session``.
+For example, we can create a Session using the ``my-sso-profile`` profile and any clients created from this session will use the ``my-sso-profile`` credentials:
+
+.. code-block:: python
+
+    import boto3
+
+    session = boto3.Session(profile_name='my-sso-profile')
+    s3_client = session.client('s3')
 
 Boto 2 config
 ---------------