clarify the achored ID36 parameters in the API

tildes/openapi_beta.yaml

@@ -214,7 +214,7 @@ components:
         schema:
           type: string
         required: false
-        description: The ID36 of the first item from the current page, to get items before it. You can only specify either `before` or `after`, not both.
+        description: The ID36 of the first item from the current page, to get items before it. You can only specify either `before` or `after`, not both. In mixed feeds like user profiles, this parameter needs a "t-" or "c-" prefix to indicate topics and comments respectively.
       
       paginationAfter:
         in: query
@@ -222,7 +222,7 @@ components:
         schema:
           type: string
         required: false
-        description: The ID36 of the last item from the previous page, to get items after it. You can only specify either `before` or `after`, not both.
+        description: The ID36 of the last item from the previous page, to get items after it. You can only specify either `before` or `after`, not both. In mixed feeds like user profiles, this parameter needs a "t-" or "c-" prefix to indicate topics and comments respectively.
       
       paginationLimit:
         in: query