add must use to several hooks

packages/signals/src/selector.rs

@@ -21,6 +21,7 @@ use crate::{get_effect_stack, signal::SignalData, CopyValue, Effect, ReadOnlySig
 ///     render! { "{double}" }
 /// }
 /// ```
+#[must_use = "Consider using `use_effect` to rerun a callback when dependencies change"]
 pub fn use_selector<R: PartialEq>(
     cx: &ScopeState,
     f: impl FnMut() -> R + 'static,
@@ -44,6 +45,7 @@ pub fn use_selector<R: PartialEq>(
 ///     render! { "{double}" }
 /// }
 /// ```
+#[must_use = "Consider using `use_effect` to rerun a callback when dependencies change"]
 pub fn use_selector_with_dependencies<R: PartialEq, D: Dependency>(
     cx: &ScopeState,
     dependencies: D,

packages/signals/src/signal.rs

@@ -43,6 +43,7 @@ use crate::{CopyValue, Effect};
 ///     }
 /// }
 /// ```
+#[must_use]
 pub fn use_signal<T: 'static>(cx: &ScopeState, f: impl FnOnce() -> T) -> Signal<T> {
     *cx.use_hook(|| Signal::new(f()))
 }