slices: mention possible memory leak in Delete doc

Mitigates golang/go#54650

Change-Id: I899094ec6af8d3b1985e737a5318e9776b4cb1a9
Reviewed-on: https://go-review.googlesource.com/c/exp/+/425895
Reviewed-by: Ian Lance Taylor <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: Deleplace

slices/slices.go

@@ -153,6 +153,9 @@ func Insert[S ~[]E, E any](s S, i int, v ...E) S {
 // Delete modifies the contents of the slice s; it does not create a new slice.
 // Delete is O(len(s)-j), so if many items must be deleted, it is better to
 // make a single call deleting them all together than to delete one at a time.
+// Delete might not modify the elements s[len(s)-(j-i):len(s)]. If those
+// elements contain pointers you might consider zeroing those elements so that
+// objects they reference can be garbage collected.
 func Delete[S ~[]E, E any](s S, i, j int) S {
 	_ = s[i:j] // bounds check