The most important rule of contributing to the developer documentation on MDN is this:

Don’t be afraid to contribute, even if you can’t write well and can’t make it beautiful. It’s easier for the writing team to clean up information written by true experts than it is to become experts ourselves.

Seriously. There aren’t that many of us on the writing team, even including our awesome non-staff contributors. We sadly don’t have enough time to become experts at all the things that need to be documented on MDN.

Even if all you do is copy your notes onto a page on MDN and click “Save,” that’s a huge help for us. Even pasting raw text into the wiki is better than not helping at all. Honest!

We’ll review your contribution and fix everything, including:

• Grammar; you don’t have to have perfect (or even good) writing skills—that’s what the writing team is here for!
• Style; we’ll make sure the content matches the MDN style guide.
• Organization; we’ll move your content, if appropriate, so that it’s in the right place on the site.
• Cross-linking; we’ll add links to other related content.
• Structure and frills; we’ll ensure that the layout and structure of your article is consistent, and that it uses any advanced wiki features that can help get the point across (such as live samples and macros).

It’s not your job to make awesome documentation. That’s our job. So don’t let fear of prevent you from sharing what you know.

http://www.bitstampede.com/2014/02/21/dont-be-afraid-to-share/