chore/doc-module: sts_assume_role.py (#62475)

Update `Example` section with with the correct module usage.

lib/ansible/modules/cloud/amazon/sts_assume_role.py

@@ -86,20 +86,20 @@ EXAMPLES = '''
 # Note: These examples do not set authentication details, see the AWS Guide for details.
 
 # Assume an existing role (more details: https://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRole.html)
-sts_assume_role:
-  role_arn: "arn:aws:iam::123456789012:role/someRole"
-  role_session_name: "someRoleSession"
-register: assumed_role
+- sts_assume_role:
+    role_arn: "arn:aws:iam::123456789012:role/someRole"
+    role_session_name: "someRoleSession"
+  register: assumed_role
 
 # Use the assumed role above to tag an instance in account 123456789012
-ec2_tag:
-  aws_access_key: "{{ assumed_role.sts_creds.access_key }}"
-  aws_secret_key: "{{ assumed_role.sts_creds.secret_key }}"
-  security_token: "{{ assumed_role.sts_creds.session_token }}"
-  resource: i-xyzxyz01
-  state: present
-  tags:
-    MyNewTag: value
+- ec2_tag:
+    aws_access_key: "{{ assumed_role.sts_creds.access_key }}"
+    aws_secret_key: "{{ assumed_role.sts_creds.secret_key }}"
+    security_token: "{{ assumed_role.sts_creds.session_token }}"
+    resource: i-xyzxyz01
+    state: present
+    tags:
+      MyNewTag: value
 
 '''