fix(pubsublite): update the API

#### pubsublite:v1
The following keys were changed:
- schemas.PartitionConfig.properties.scale.description

discovery/pubsublite-v1.json

@@ -555,7 +555,7 @@
       }
     }
   },
-  "revision": "20200803",
+  "revision": "20200818",
   "rootUrl": "https://pubsublite.googleapis.com/",
   "schemas": {
     "Capacity": {
@@ -700,7 +700,7 @@
           "type": "string"
         },
         "scale": {
-          "description": "Every partition in the topic is allocated throughput equivalent to `scale` times the standard partition throughput (4 MiB/s). This is also reflected in the cost of this topic; a topic with `scale` of 2 and count of 10 is charged for 20 partitions. This value must be in the range [1,4].",
+          "description": "DEPRECATED: Use capacity instead which can express a superset of configurations. Every partition in the topic is allocated throughput equivalent to `scale` times the standard partition throughput (4 MiB/s). This is also reflected in the cost of this topic; a topic with `scale` of 2 and count of 10 is charged for 20 partitions. This value must be in the range [1,4].",
           "format": "int32",
           "type": "integer"
         }

src/apis/pubsublite/v1.ts

@@ -229,7 +229,7 @@ export namespace pubsublite_v1 {
      */
     count?: string | null;
     /**
-     * Every partition in the topic is allocated throughput equivalent to `scale` times the standard partition throughput (4 MiB/s). This is also reflected in the cost of this topic; a topic with `scale` of 2 and count of 10 is charged for 20 partitions. This value must be in the range [1,4].
+     * DEPRECATED: Use capacity instead which can express a superset of configurations. Every partition in the topic is allocated throughput equivalent to `scale` times the standard partition throughput (4 MiB/s). This is also reflected in the cost of this topic; a topic with `scale` of 2 and count of 10 is charged for 20 partitions. This value must be in the range [1,4].
      */
     scale?: number | null;
   }