Clarifiy weak pointers being diassociated…

…noting the fact that `clone` is not called.

Co-authored-by: Mark Rousskov <mark.simulacrum@gmail.com>

Author: steffahn

library/alloc/src/rc.rs

@@ -1100,8 +1100,9 @@ impl<T: Clone> Rc<T> {
     /// [`clone`] the inner value to a new allocation to ensure unique ownership.  This is also
     /// referred to as clone-on-write.
     ///
-    /// If there are no other `Rc` pointers to this allocation, then [`Weak`]
-    /// pointers to this allocation will be disassociated.
+    /// However, if there are no other `Rc` pointers to this allocation, but some [`Weak`]
+    /// pointers, then the [`Weak`] pointers will be disassociated and the inner value will not
+    /// be cloned.
     ///
     /// See also [`get_mut`], which will fail rather than cloning.
     ///

library/alloc/src/sync.rs

@@ -1350,8 +1350,9 @@ impl<T: Clone> Arc<T> {
     /// [`clone`] the inner value to a new allocation to ensure unique ownership.  This is also
     /// referred to as clone-on-write.
     ///
-    /// If there are no other `Arc` pointers to this allocation, then [`Weak`]
-    /// pointers to this allocation will be disassociated.
+    /// However, if there are no other `Arc` pointers to this allocation, but some [`Weak`]
+    /// pointers, then the [`Weak`] pointers will be disassociated and the inner value will not
+    /// be cloned.
     ///
     /// See also [`get_mut`], which will fail rather than cloning.
     ///