A minor release.
There is a known issue with assigned interfaces losing their address(es) during system startup. Until this is fixed, you will need to re-save the assigned interface and apply settings.
This has also been tested on pfSense 2.5.1 (non-RC) and the latest 2.6.0 development snapshots.
Get all of these packages onto your pfSense box and run
pkg add pfSense-pkg-WireGuard-0.0.4_1.txz