Yes, it is possible to contribute your own tutorial by creating a project on openhardware.io (it shares the same database as mysensors.org) and submit it for review. After publishing, I can "move" it to the mysensors.org site and you can continue editing it.
For long time contributors we can offer full editor rights which means you can update any article on the site. It's a bit scary to hand out this right to anyone so you'd have to prove yourself first
If something is wrong in the current articles, you can of cause pm us the error to be corrected.