added better documentation and code snipppets for the use_resource, use_future, use_effect and use_context hooks

packages/signals/tests/create.rs

@@ -1,5 +1,8 @@
 #![allow(unused, non_upper_case_globals, non_snake_case)]
 
+use std::collections::HashMap;
+use std::sync::Arc;
+
 use dioxus::prelude::*;
 use dioxus_core::ElementId;
 use dioxus_core::NoOpMutations;