Remove extraneous quotes, fix a typo

filter.yaml: quotes under |- were taken literally.
notifications.yaml: it's a number in the example, not a string

api/client-server/filter.yaml

@@ -119,7 +119,7 @@ paths:
       responses:
         200:
           description: |-
-            "The filter defintion"
+            The filter definition.
           examples:
             application/json: {
                 "room": {

api/client-server/notifications.yaml

@@ -49,7 +49,7 @@ paths:
           name: limit
           description: Limit on the number of events to return in this request.
           required: false
-          x-example: "20"
+          x-example: 20
         - in: query
           name: only
           type: string