Add description to POST /keys/signatures/upload request body

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

data/api/client-server/cross_signing.yaml

@@ -150,7 +150,6 @@ paths:
       description: |-
         Publishes cross-signing signatures for the user.
 
-        The request body is a map from user ID to key ID to signed JSON object.
         The signed JSON object must match the key previously uploaded or
         retrieved for the given key ID, with the exception of the `signatures`
         property, which contains the new signature(s) to add.
@@ -162,6 +161,8 @@ paths:
           application/json:
             schema:
               type: object
+              description: |-
+                A map of user ID to a map of key ID to signed JSON object.
               additionalProperties:
                 type: object
                 additionalProperties: