Update Readme for “Printing to Screen” post

README.md

@@ -1,12 +1,12 @@
-# Blog OS (Set Up Rust)
-[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post_3)](https://travis-ci.org/phil-opp/blog_os/branches)
+# Blog OS (Printing To Screen)
+[![Build Status](https://travis-ci.org/phil-opp/blog_os.svg?branch=post_4)](https://travis-ci.org/phil-opp/blog_os/branches)
 
-This repository contains the source code for the [Set Up Rust](http://os.phil-opp.com/set-up-rust.html) post of the [Writing an OS in Rust](http://os.phil-opp.com) series.
+This repository contains the source code for the [Printing To Screen](http://os.phil-opp.com/printing-to-screen.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 nigthly Rust compiler installed. Then you can run it using `make run`.
+You need to have `nasm`, `grub-mkrescue`, `xorriso`, `qemu`, and a nightly Rust compiler installed. Then you can run it using `make run`.
 
 Please file an issue if you have any problems.