CLOUDP-278627: Update linting

Author: blva

tools/spectral/.spectral.yaml

@@ -172,9 +172,8 @@ rules:
       - field: additionalServices
         function: pattern
         functionOptions:
-          match: "^(mms)$"
-        message: "'additionalServices' must be 'mms' as no other services are supported."
-
+          match: "^mms(,[a-zA-Z0-9_-]+)*$"
+        message: "'additionalServices' must start with 'mms' and can include additional services in a comma-separated format."
    no-slash-before-custom-method:
     description: "Custom methods (e.g., ':applyItem') should not be preceded by a '/'."
     message: "The path '{{path}}' contains a '/' before a custom method. Custom methods should not start with a '/'."