Stabilise entry_insert

Signed-off-by: Félix Saparelli <felix@passcod.name>

Author: passcod

library/std/src/collections/hash/map.rs

@@ -2450,7 +2450,6 @@ impl<'a, K, V> Entry<'a, K, V> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(entry_insert)]
     /// use std::collections::HashMap;
     ///
     /// let mut map: HashMap<&str, String> = HashMap::new();
@@ -2459,7 +2458,7 @@ impl<'a, K, V> Entry<'a, K, V> {
     /// assert_eq!(entry.key(), &"poneyland");
     /// ```
     #[inline]
-    #[unstable(feature = "entry_insert", issue = "65225")]
+    #[stable(feature = "entry_insert", since = "1.58.0")]
     pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V> {
         match self {
             Occupied(mut entry) => {
@@ -2793,7 +2792,6 @@ impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(entry_insert)]
     /// use std::collections::HashMap;
     /// use std::collections::hash_map::Entry;
     ///
@@ -2805,7 +2803,7 @@ impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V> {
     /// assert_eq!(map["poneyland"], 37);
     /// ```
     #[inline]
-    #[unstable(feature = "entry_insert", issue = "65225")]
+    #[stable(feature = "entry_insert", since = "1.58.0")]
     pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V> {
         let base = self.base.insert_entry(value);
         OccupiedEntry { base }