api: set the api_doc before registering any api

This is a left over from the re ordering of the API init.  The api_doc
should be set first, so later API registration will enable their
relevent swagger doc.

Currently, the swagger documentation of the system API is not available.

Fixes #1160

Signed-off-by: Amnon Heiman <amnon@scylladb.com>
Message-Id: <1459750490-15996-1-git-send-email-amnon@scylladb.com>

api/api.cc

@@ -61,10 +61,10 @@ future<> set_server_init(http_context& ctx) {
                 new content_replace("html")));
         r.add(GET, url("/ui").remainder("path"), new httpd::directory_handler(ctx.api_dir,
                 new content_replace("html")));
+        rb->set_api_doc(r);
         rb->register_function(r, "system",
                 "The system related API");
         set_system(ctx, r);
-        rb->set_api_doc(r);
     });
 }