Add code block in README

README.md

@@ -4,9 +4,11 @@ Check system configuration for a gentoo machine (VM or PHYSICAL) based on GRIFON
 It's a Gentoo OS configuration recipe. This script normally doesn't modify anything on the system.
 
 To use (with root user) :   
+```
 mv ./vars.example ./vars.sh  
 vim  ./vars.sh # Edit all values which will be used by the script  
 ./recipe_gentoo.sh [--physical]  
+```
 
 If you cannot execute the script, add the 'x' permission for the user (chmod u+x ./recipe_gentoo.sh).