Update map.rs

Author: Xylenox

library/alloc/src/collections/btree/map.rs

@@ -2670,6 +2670,8 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
     /// Passing `Bound::Unbounded` will return a cursor pointing to the
     /// gap before the smallest key in the map.
     ///
+    /// Represents the gap at the beginning of a range with the given bound as it's lower bound.
+    ///
     /// # Examples
     ///
     /// ```
@@ -2723,6 +2725,8 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
     /// Passing `Bound::Unbounded` will return a cursor pointing to the
     /// gap before the smallest key in the map.
     ///
+    /// Represents the gap at the beginning of a range with the given bound as it's lower bound.
+    ///
     /// # Examples
     ///
     /// ```
@@ -2793,6 +2797,8 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
     /// Passing `Bound::Unbounded` will return a cursor pointing to the
     /// gap after the greatest key in the map.
     ///
+    /// Represents the gap at the end of a range with the given bound as it's upper bound.
+    ///
     /// # Examples
     ///
     /// ```
@@ -2846,6 +2852,8 @@ impl<K, V, A: Allocator + Clone> BTreeMap<K, V, A> {
     /// Passing `Bound::Unbounded` will return a cursor pointing to the
     /// gap after the greatest key in the map.
     ///
+    /// Represents the gap at the end of a range with the given bound as it's upper bound.
+    ///
     /// # Examples
     ///
     /// ```