Add doc comments about safest way to initialize a vector of zeros

diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs
index 2bc037e3fee126343715212911c8b62e1d28867e..3188de512662c9290deafc77bc3b39fbdc4d3f75 100644 (file)
--- a/src/liballoc/vec.rs
+++ b/src/liballoc/vec.rs
@@ -120,7 +120,9 @@
 /// assert_eq!(vec, [1, 2, 3, 4]);
 /// ```
 ///
-/// It can also initialize each element of a `Vec<T>` with a given value:
+/// It can also initialize each element of a `Vec<T>` with a given value.
+/// Initializing a `Vec<T>` in this manner is the most efficient and safest way to allocate a
+/// vector of zeros as previously zeroed memory is requested from the operating system:
 ///
 /// ```
 /// let vec = vec![0; 5];