MAINTAINERS: wifi: ath12k: add wiki link

The ath12k wireless driver now has a wiki, so advertise it.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230829-ath12kwiki-v1-1-df37127527a1@quicinc.com

MAINTAINERS

@@ -17528,6 +17528,7 @@ M:	Kalle Valo <kvalo@kernel.org>
 M:	Jeff Johnson <quic_jjohnson@quicinc.com>
 L:	ath12k@lists.infradead.org
 S:	Supported
+W:	https://wireless.wiki.kernel.org/en/users/Drivers/ath12k
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git
 F:	drivers/net/wireless/ath/ath12k/