fixed instructions for mac

Former-commit-id: f71b3f0d03880f6411b4b50f4e5a05ebbf898e1e

include/igl/matlabinterface.h

@@ -12,7 +12,7 @@
 
 // MAC ONLY:
 // Add to the environment variables:
-// DYLD_LIBRARY_PATH =  
+// DYLD_LIBRARY_PATH = /Applications/MATLAB_R2011a.app/bin/maci64/
 // PATH = /opt/local/bin:/opt/local/sbin:/Applications/MATLAB_R2011a.app/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/texbin:/usr/X11/bin
 
 #ifndef IGL_MATLAB_INTERFACE_H