std::collections docs: Address issues that came up in PR #41286

* Bound:
  * Added another example using RangeArgument to illustrate how Bound maps
    to range endpoints.
  * Added a note to the existing example that says that it's better to use
    range syntax in most cases
  * Added missing /// line
* binary_heap::PeakMut: s/Object representing/Structure wrapping
* added collections/hash_set/struct.HashSet.html to linkchecker whitelist

src/libcollections/binary_heap.rs

@@ -219,7 +219,7 @@ pub struct BinaryHeap<T> {
     data: Vec<T>,
 }
 
-/// Object representing a mutable reference to the greatest item on a
+/// Structure wrapping a mutable reference to the greatest item on a
 /// `BinaryHeap`.
 ///
 /// This `struct` is created by the [`peek_mut`] method on [`BinaryHeap`]. See

src/libcollections/lib.rs

@@ -135,8 +135,25 @@ mod std {
 }
 
 /// An endpoint of a range of keys.
+///
 /// # Examples
 ///
+/// `Bound`s are range endpoints:
+///
+/// ```
+/// #![feature(collections_range)]
+///
+/// use std::collections::range::RangeArgument;
+/// use std::collections::Bound::*;
+///
+/// assert_eq!((..100).start(), Unbounded);
+/// assert_eq!((1..12).start(), Included(&1));
+/// assert_eq!((1..12).end(), Excluded(&12));
+/// ```
+///
+/// Using a tuple of `Bound`s as an argument to [`BTreeMap::range`].
+/// Note that in most cases, it's better to use range syntax (`1..5`) instead.
+///
 /// ```
 /// use std::collections::BTreeMap;
 /// use std::collections::Bound::{Excluded, Included, Unbounded};
@@ -152,6 +169,8 @@ mod std {
 ///
 /// assert_eq!(Some((&3, &"a")), map.range((Unbounded, Included(5))).next());
 /// ```
+///
+/// [`BTreeMap::range`]: btree_map/struct.BTreeMap.html#method.range
 #[stable(feature = "collections_bound", since = "1.17.0")]
 #[derive(Clone, Copy, Debug, Hash, PartialEq, Eq)]
 pub enum Bound<T> {

src/tools/linkchecker/main.rs

@@ -142,7 +142,8 @@ fn check(cache: &mut Cache,
     if file.ends_with("btree_set/struct.BTreeSet.html") ||
        file.ends_with("collections/struct.BTreeSet.html") ||
        file.ends_with("collections/btree_map/struct.BTreeMap.html") ||
-       file.ends_with("collections/hash_map/struct.HashMap.html") {
+       file.ends_with("collections/hash_map/struct.HashMap.html") ||
+       file.ends_with("collections/hash_set/struct.HashSet.html") {
         return None;
     }