Merge pull request NetSys#810 from NetSys/fix_readme

Fix broken link

README.md

@@ -5,7 +5,7 @@
 
 BESS (formerly known as [SoftNIC](https://www2.eecs.berkeley.edu/Pubs/TechRpts/2015/EECS-2015-155.html)) is a modular framework for software switches. BESS itself is *not* a virtual switch; it is neither pre-configured nor hardcoded to provide particular functionality, such as Ethernet bridging or OpenFlow-driven switching. Instead, you (or an external controller) can *configure* your own packet processing datapath by composing small "modules". While the basic concept is similar to [Click](http://read.cs.ucla.edu/click/click), BESS does not sacrifice performance for programmability.
 
-BESS was created by Sangjin Han and is developed at the University of California, Berkeley and at Nefeli Networks. [Contributors to BESS](https://github.com/NetSys/bess/blob/master/CONTRIBUTORS.md) include students, researchers, and developers who care about networking with high performance and high customizability. BESS is open-source under a BSD license.
+BESS was created by Sangjin Han and is developed at the University of California, Berkeley and at Nefeli Networks. [Contributors to BESS](https://github.com/NetSys/bess/blob/master/CONTRIBUTING.md) include students, researchers, and developers who care about networking with high performance and high customizability. BESS is open-source under a BSD license.
 
 If you are new to BESS, we recommend you start here: