Adding feature flags that are required for GMA

doc/user/group/saml_sso/group_managed_accounts.md

@@ -52,11 +52,13 @@ assertions to be able to create a user.
 
 ## Feature flag **(PREMIUM ONLY)**
 
-The group-managed accounts feature is behind a feature flag: `group_managed_accounts`. The flag is disabled by default.
+The group-managed accounts feature is behind these feature flags: `group_managed_accounts`, `sign_up_on_sso` and `convert_user_to_group_managed_accounts`. The flags are disabled by default.
 To activate the feature, ask a GitLab administrator with Rails console access to run:
 
 ```ruby
 Feature.enable(:group_managed_accounts)
+Feature.enable(:sign_up_on_sso)
+Feature.enable(:convert_user_to_group_managed_accounts)
 ```
 
 ## Project restrictions for Group-managed accounts