auto merge of #13416 : brson/rust/30min, r=alexcrichton

This is intended to be the first thing somebody new to the language reads about Rust. It is supposed to be simple and intriguing, to give the user an idea of whether Rust is appropriate for them, and to hint that there's a lot of cool stuff to learn if they just keep diving deeper.

I'm particularly happy with the sequence of concurrency examples.

Author: bors

mk/docs.mk

@@ -26,7 +26,7 @@
 # L10N_LANGS are the languages for which the docs have been
 # translated.
 ######################################################################
-DOCS := index tutorial guide-ffi guide-macros guide-lifetimes \
+DOCS := index intro tutorial guide-ffi guide-macros guide-lifetimes \
 	guide-tasks guide-container guide-pointers guide-testing \
 	guide-runtime complement-bugreport complement-cheatsheet \
 	complement-lang-faq complement-project-faq rust rustdoc \

src/doc/index.md

@@ -7,6 +7,7 @@
 li {list-style-type: none; }
 </style>
 
+* [A 30-minute Intro to Rust](intro.html)
 * [The Rust tutorial](tutorial.html)  (* [PDF](tutorial.pdf))
 * [The Rust reference manual](rust.html) (* [PDF](rust.pdf))