Fix typo

Author: okaneco

palette/src/rgb/packed.rs

@@ -51,7 +51,7 @@ use crate::Pixel;
 /// type will disregard the alpha value.
 ///
 /// `Packed` implements [Pixel](encoding/pixel/trait.Pixel.html) and can be
-/// contructed from a slice of `&[u32]`.
+/// constructed from a slice of `&[u32]`.
 ///
 /// ```
 /// use palette::{Packed, Pixel};