Odds are you'll be able to contribute somewhere. I've only just started editing some things but I see other people adding stuff too on the "Recent changes" page.
Some items and images haven't been updated for 1.0 yet, that'd be a quick way to get started. And there's a list of pages marked as a "stub" here, that could use expansion: https://rimworldwiki.com/wiki/Category:Page_Stub
Check around, maybe something will fall within your areas of interest and/or knowledge!