MAINTAINERS: soc: reference maintainer profile

Mention the SoC maintainer profile in P: entry.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230723131924.78190-1-krzysztof.kozlowski@linaro.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>

MAINTAINERS

@@ -1558,6 +1558,7 @@ M:	Olof Johansson <olof@lixom.net>
 M:	soc@kernel.org
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
+P:	Documentation/process/maintainer-soc.rst
 C:	irc://irc.libera.chat/armlinux
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git
 F:	Documentation/process/maintainer-soc.rst