fix double comment characters (#17484)

# Objective
- Improve docs by removing duplicate comment characters
- Fixes #17483

## Solution
- Replaced `/// ///` with `///`

crates/bevy_ecs/src/change_detection.rs

@@ -675,7 +675,7 @@ impl_debug!(Res<'w, T>, Resource);
 /// If you need a shared borrow, use [`Res`] instead.
 ///
 /// This [`SystemParam`](crate::system::SystemParam) fails validation if resource doesn't exist.
-/// /// This will cause a panic, but can be configured to do nothing or warn once.
+/// This will cause a panic, but can be configured to do nothing or warn once.
 ///
 /// Use [`Option<ResMut<T>>`] instead if the resource might not always exist.
 pub struct ResMut<'w, T: ?Sized + Resource> {
@@ -736,7 +736,7 @@ impl<'w, T: Resource> From<ResMut<'w, T>> for Mut<'w, T> {
 /// over to another thread.
 ///
 /// This [`SystemParam`](crate::system::SystemParam) fails validation if non-send resource doesn't exist.
-/// /// This will cause a panic, but can be configured to do nothing or warn once.
+/// This will cause a panic, but can be configured to do nothing or warn once.
 ///
 /// Use [`Option<NonSendMut<T>>`] instead if the resource might not always exist.
 pub struct NonSendMut<'w, T: ?Sized + 'static> {

crates/bevy_ecs/src/entity/hash_map.rs

@@ -149,7 +149,7 @@ impl<V> IntoIterator for EntityHashMap<V> {
 /// An iterator over the keys of a [`EntityHashMap`] in arbitrary order.
 /// The iterator element type is `&'a Entity`.
 ///
-/// /// This struct is created by the [`keys`] method on [`EntityHashMap`]. See its documentation for more.
+/// This struct is created by the [`keys`] method on [`EntityHashMap`]. See its documentation for more.
 ///
 /// [`keys`]: EntityHashMap::keys
 pub struct Keys<'a, V, S = EntityHash>(hash_map::Keys<'a, Entity, V>, PhantomData<S>);

crates/bevy_ecs/src/system/query.rs

@@ -1902,7 +1902,7 @@ impl<'w, 'q, Q: QueryData, F: QueryFilter> From<&'q mut Query<'w, '_, Q, F>>
 /// [System parameter] that provides access to single entity's components, much like [`Query::single`]/[`Query::single_mut`].
 ///
 /// This [`SystemParam`](crate::system::SystemParam) fails validation if zero or more than one matching entity exists.
-/// /// This will cause a panic, but can be configured to do nothing or warn once.
+/// This will cause a panic, but can be configured to do nothing or warn once.
 ///
 /// Use [`Option<Single<D, F>>`] instead if zero or one matching entities can exist.
 ///
@@ -1938,7 +1938,7 @@ impl<'w, D: QueryData, F: QueryFilter> Single<'w, D, F> {
 /// [System parameter] that works very much like [`Query`] except it always contains at least one matching entity.
 ///
 /// This [`SystemParam`](crate::system::SystemParam) fails validation if no matching entities exist.
-/// /// This will cause a panic, but can be configured to do nothing or warn once.
+/// This will cause a panic, but can be configured to do nothing or warn once.
 ///
 /// Much like [`Query::is_empty`] the worst case runtime will be `O(n)` where `n` is the number of *potential* matches.
 /// This can be notably expensive for queries that rely on non-archetypal filters such as [`Added`](crate::query::Added) or [`Changed`](crate::query::Changed)

crates/bevy_ecs/src/system/system_param.rs

@@ -1397,7 +1397,7 @@ unsafe impl<T: SystemBuffer> SystemParam for Deferred<'_, T> {
 /// over to another thread.
 ///
 /// This [`SystemParam`] fails validation if non-send resource doesn't exist.
-/// /// This will cause a panic, but can be configured to do nothing or warn once.
+/// This will cause a panic, but can be configured to do nothing or warn once.
 ///
 /// Use [`Option<NonSend<T>>`] instead if the resource might not always exist.
 pub struct NonSend<'w, T: 'static> {