docs: Remove tokio from examples
@@ -10,10 +10,8 @@ Apollo Federation is a GraphQL architecture for combining multiple GraphQL servi
```rust
# extern crate async_graphql;
-# extern crate tokio;
# use async_graphql::*;
-#[tokio::main]
-async fn main() {
+fn main() {
let schema = Schema::build(EmptyQuery, EmptyMutation, EmptySubscription)
.enable_federation()
.finish();
