Add description and license fields to OpenAPI spec.

These were added earlier to the control plane's copy of this file.
This is the master version of this file, so let's keep it in sync.

pageserver/src/http/openapi_spec.yml

@@ -1,7 +1,11 @@
 openapi: "3.0.2"
 info:
   title: Page Server API
+  description: Neon Pageserver API
   version: "1.0"
+  license:
+    name: "Apache"
+    url: https://github.com/neondatabase/neon/blob/main/LICENSE
 servers:
   - url: ""
 paths: