Change path of nodeinfo to use .json format

lib/pleroma/web/nodeinfo/nodeinfo_controller.ex

@@ -12,7 +12,7 @@ def schemas(conn, _params) do
       links: [
         %{
           rel: "http://nodeinfo.diaspora.software/ns/schema/2.0",
-          href: Web.base_url() <> "/nodeinfo/2.0"
+          href: Web.base_url() <> "/nodeinfo/2.0.json"
         }
       ]
     }