doc: suggest try_reserve in try_reserve_exact

Signed-off-by: TennyZhuang <zty0826@gmail.com>

library/alloc/src/collections/vec_deque/mod.rs

@@ -720,9 +720,9 @@ impl<T, A: Allocator> VecDeque<T, A> {
     ///
     /// Note that the allocator may give the collection more space than it
     /// requests. Therefore, capacity can not be relied upon to be precisely
-    /// minimal. Prefer [`reserve`] if future insertions are expected.
+    /// minimal. Prefer [`try_reserve`] if future insertions are expected.
     ///
-    /// [`reserve`]: VecDeque::reserve
+    /// [`try_reserve`]: VecDeque::try_reserve
     ///
     /// # Errors
     ///

library/alloc/src/string.rs

@@ -1044,9 +1044,9 @@ impl String {
     ///
     /// Note that the allocator may give the collection more space than it
     /// requests. Therefore, capacity can not be relied upon to be precisely
-    /// minimal. Prefer [`reserve`] if future insertions are expected.
+    /// minimal. Prefer [`try_reserve`] if future insertions are expected.
     ///
-    /// [`reserve`]: String::reserve
+    /// [`try_reserve`]: String::try_reserve
     ///
     /// # Errors
     ///

library/alloc/src/vec/mod.rs

@@ -881,9 +881,9 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// Note that the allocator may give the collection more space than it
     /// requests. Therefore, capacity can not be relied upon to be precisely
-    /// minimal. Prefer [`reserve`] if future insertions are expected.
+    /// minimal. Prefer [`try_reserve`] if future insertions are expected.
     ///
-    /// [`reserve`]: Vec::reserve
+    /// [`try_reserve`]: Vec::try_reserve
     ///
     /// # Errors
     ///