Bug 991287 - Update links on webmaker.org/mentor page

https://bugzilla.mozilla.org/show_bug.cgi?id=991287
It's really hard to say whether or not to keep the entities or use regular quote if we are talking about translators since most of them (or all of them) never complain or got confused when we have entities in the strings simply because they will translate them and don't use entities in their language anyway (especially in Thai).

So, I still think we should avoid any confusion that can cause but as long as we are clear with our translators on the instruction.