Update Readme for “Double Faults” post

README.md

@@ -1,12 +1,14 @@
-# Blog OS (Handling Exceptions)
-[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post_9)](https://travis-ci.org/phil-opp/blog_os/branches)
+# Blog OS (Double Faults)
+[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post_10)](https://travis-ci.org/phil-opp/blog_os/branches)
 
-This repository contains the source code for the [Handling Exceptions](http://os.phil-opp.com/handling-exceptions.html) post of the [Writing an OS in Rust](http://os.phil-opp.com) series.
+This repository contains the source code for the [Double Faults](http://os.phil-opp.com/double-faults.html) post of the [Writing an OS in Rust](http://os.phil-opp.com) series.
 
 **Check out the [master branch](https://github.com/phil-opp/blog_os) for more information.**
 
 ## Building
-You need to have `nasm`, `grub-mkrescue`, `xorriso`, `qemu`, and a nightly Rust compiler installed. Then you can run it using `make run`.
+You need to have `nasm`, `grub-mkrescue`, `xorriso`, `qemu`, a nightly Rust compiler, and [xargo] installed. Then you can run it using `make run`.
+
+[xargo]: https://github.com/japaric/xargo
 
 Please file an issue if you have any problems.