Auto merge of #28840 - rust-lang:brson-patch-1, r=steveklabnik

Add the Tock paper.

Author: bors

src/doc/trpl/bibliography.md

@@ -79,3 +79,4 @@ Language](http://www.cs.indiana.edu/~eholk/papers/hips2013.pdf). Early GPU work
 * [Session Types for
   Rust](http://munksgaard.me/papers/laumann-munksgaard-larsen.pdf). Philip
   Munksgaard's master's thesis. Research for Servo.
+* [Ownership is Theft: Experiences Building an Embedded OS in Rust - Amit Levy, et. al.](http://amitlevy.com/papers/tock-plos2015.pdf)