Comments can be explicit, but without compromising readability direct.

* Adding a new rule in CONTRIBUTING file
   -- 80 colums or 70 if too small
* Adding an example of comments style
   -- comments between two commands is prohibited. :@
   -- before functions or blocks.
   -- a new line before and after comments


(? Later, if time is here, i'll implemente a .sh to have Makefile for this specific project, but also for C, C++, whatever projects ... :) )