Many micro fixes

Hi, these are plenty of micro-fixes:
* typos
* grammar
* s/librairie/bibliothèque/

I've also added some french conferences: @rulu @la_conf @dotrb
Please feel free to edit descriptions, MM. @fcat @tigrish and @sylvinus!

I'd love to add more french initiation links @simonc @berlimioz

There are plenty of "programmeur":
 I'd like to spark the debate of replacing them all with "développeur".

Thanks! :heart: