I use Wikipedia all the time but rearely contribute. It feels like another place. I think that I could read and use, but am not really qualified to contribute toward.
A Wikia like this is a great place to get started. Because the scope is so narrow in what the wiki contains, we as the common folk don;t need to be experts on any particular topic to be helpful. The most important driver is passion for the Expanse - either the books or the show. Oh, I guess speaking and reading English helps too. :)
But really, just have a look at the pages. See a typo? Make an edit.
See a character that doesn;t have a full name listed? Make an edit.
See something that is flat-out incorrect? Make an edit.
When the show premieres in December, this place is going to get a lot of attention. A huge uptick in traffic. Your help now will get seen and used by thousands, and that work will enhance their enjoyment of the books and show.
You can make a difference!