auto merge of #5773 : dunsmoreb/rust/incoming, r=bstrie

Updates the tutorial to include a simple definition for tuples in section 4.2. Fixes #5132.

Author: bors

doc/tutorial.md

@@ -495,7 +495,11 @@ omitted.
 
 A powerful application of pattern matching is *destructuring*:
 matching in order to bind names to the contents of data
-types. Assuming that `(float, float)` is a tuple of two floats:
+types.
+
+> ***Note:*** The following code makes use of tuples (`(float, float)`) which
+> are explained in section 5.3. For now you can think of tuples as a list of
+> items.
 
 ~~~~
 fn angle(vector: (float, float)) -> float {