Rollup merge of rust-lang#52218 - rivertam:patch-1, r=withoutboats

Amend option.take examples

It wasn't abundantly clear to me what `.take` returned. Perhaps this is a slightly frivolous change, but I think it's an improvement. =)

Apologies if I'm not following proper procedures.

src/libcore/option.rs

@@ -833,12 +833,14 @@ impl<T> Option<T> {
     ///
     /// ```
     /// let mut x = Some(2);
-    /// x.take();
+    /// let y = x.take();
     /// assert_eq!(x, None);
+    /// assert_eq!(y, Some(2));
     ///
     /// let mut x: Option<u32> = None;
-    /// x.take();
+    /// let y = x.take();
     /// assert_eq!(x, None);
+    /// assert_eq!(y, None);
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]