config.5: Bump .Dd to reflect latest update

MFC with:       7d7b2d38463c ("config.5: Document CONF_CFLAGS under 'makeoptions'")
Event:          Kitchener-Waterloo Hackathon 202506
Sponsored by:   The FreeBSD Foundation

usr.sbin/config/config.5

@@ -21,7 +21,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd February 10, 2025
+.Dd June 13, 2025
 .Dt CONFIG 5
 .Os
 .Sh NAME