Update specification.md

Co-authored-by: Ricardo Zanini <[email protected]>

Author: cdavernas

specification.md

@@ -4729,7 +4729,7 @@ errors:
   policies:
     - name: 'my-retry-policy'
       handlers:
-	      - refName: 'handle-timeout-error'
+            - refName: 'handle-timeout-error'
         - when:
       	    - status: 503
           retry: 'my-retry-policy'