Rooting Marshmallow devices could be a pain in the ass, but thanks to Team its much more simpler and easier, as they have successfully rooted the Gionee M5 Mini Marshmallow via CWM recovery.

Before proceeding with this guide, ensure your build number (Settings > About phone > Build number) is as follows

http://www.droidgurus.com/2017/01/how-to-install-cwm-recovery-and-root.html?m=1