The dataref documentation on the X-Plane SDK website is updated for each release of X-Plane 9.
X-Plane 930 has not yet been released. It is a "release candidate" but since we haven't signed off on it yet, 922r1 is still the most current real release of X-Plane, and it's what users get when they update without asking for a beta. So the website has 922 datarefs.
Since version 9, every release of X-Plane (including betas and RCs) has a copy of datarefs.txt in the plugins folder that is correct for that release. In other words, the docs that ship with X-Plane and the sim itself are always in sync.
So for now use datarefs.txt in the 930 RC 2 plugins folder! When 930 goes final, the website will be updated.