Update partially initialized values in drop documentation.

Author: ehuss

src/destructors.md

@@ -3,8 +3,8 @@
 When an [initialized] [variable] in Rust goes out of scope or a [temporary]
 is no longer needed its _destructor_ is run. [Assignment] also runs the
 destructor of its left-hand operand, unless it's an uninitialized variable. If a
-[struct] variable has been partially initialized, only its initialized fields
-are dropped.
+variable has been partially initialized, only its initialized fields are
+dropped.
 
 The destructor of a type consists of
 
@@ -63,10 +63,11 @@ loop {
     moved = ShowOnDrop("Drops when moved");
     // drops now, but is then uninitialized
     moved;
+    // Uninitialized does not drop.
     let uninitialized: ShowOnDrop;
     // Only first element drops
-    let mut partially_initialized: (ShowOnDrop, ShowOnDrop);
-    partially_initialized.0 = ShowOnDrop("Partial tuple first");
+    let mut partially_initialized = (ShowOnDrop("one"), ShowOnDrop("two"));
+    core::mem::forget(partially_initialized.1);
 }
 ```