Updated Slave (markdown)

Slave.md

@@ -16,9 +16,14 @@
 
 ## Benchmark locally
 
+#### DNS Config
+
+When you want to run browser benchmarks you need to add the lines in [slave/hosts](https://github.com/h4writer/arewefastyet/blob/master/slave/hosts). to your `/etc/hosts` (or windows equivalent) file and flush DNS cache. 
+
 #### Prerequisites
+_Note: this includes the prerequisites to download and execute browser builds, but not the ones needed to compile a shell build. For those follow the instructions at [Mozilla prerequisites](https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Linux_Prerequisites)_
+
 In order to benchmark locally you need to install some prerequisites. 
-Note: this includes the prerequisites to download and execute browser builds, but not the ones needed to compile a shell build. For those follow the instructions at [Mozilla prerequisites](https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Linux_Prerequisites)
 
 Linux
 * sudo apt-get install python2.7 python-requests git mercurial svn