Add info about GitHub authentication_type

Author: leslitagordita

openapi.yaml

@@ -17456,9 +17456,16 @@ components:
           type: string
           enum:
           - password
+          - github
           description: |
-            This account's Cloud Manager authentication type. Currently, a user's password
-            (in conjunction with their username) is the only available authentication type.
+            This account's Cloud Manager authentication type. Authentication types are chosen through
+            Cloud Manager and authorized when logging into your account. These authentication types are either
+            the user's password (in conjunction with their username), or the name of their
+            indentity provider such as GitHub. For example, if a user:
+
+            - Has never used Third-Party Authentication, their authentication type will be `password`.
+            - Is using Third-Party Authentication, their authentication type will be the name of their Identity Provider (eg. `github`).
+            - Has used Third-Party Authentication and has since revoked it, their authentication type will be `password`.
           example: password
           readOnly: true
     Region: