add a note to the README about this being a tutorial for an ancient version of Rust

diff --git a/README.md b/README.md
index 494099fd94eebaee3c068601dd48b63d147d9664..c163e7f6c1b67d57c529e5800e7a844e84c6bfd2 100644 (file)
--- a/README.md
+++ b/README.md
@@ -3,6 +3,9 @@
 This documents Rust-101, a tutorial for the [Rust
 language](http://www.rust-lang.org/).
 
+**Note that this tutorial was written for Rust 1.3 in 2015, and the language evolved a lot since then.
+Some of the idioms presented here may no longer reflect current practice.**
+
 ## Online tutorial
 
 The most accessible form of the tutorial is its