Docs: add backport notice in module umount docs (#1476)

This aims to uniform the documentation since the official introduction
of pre-GKI modules umount feature

kernel/Makefile

@@ -62,7 +62,7 @@ ifeq ($(shell grep -q "int path_umount" $(srctree)/fs/namespace.c; echo $$?),0)
 ccflags-y += -DKSU_UMOUNT
 else
 $(info -- Did you know you can backport path_umount to fs/namespace.c from 5.9?)
-$(info -- Read: https://kernelsu.org/guide/how-to-integrate-for-non-gki.html#path_umount)
+$(info -- Read: https://kernelsu.org/guide/how-to-integrate-for-non-gki.html#how-to-backport-path_umount)
 endif
 
 ccflags-y += -Wno-implicit-function-declaration -Wno-strict-prototypes -Wno-int-conversion -Wno-gcc-compat