docs: admin-guide: add kdump documentation into it

The Kdump documentation describes procedures with admins use
in order to solve issues on their systems.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 6425871..20afd60 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -2036,7 +2036,7 @@
 	  kdump/kexec. The crash dump kernel must be compiled to a
 	  memory address not used by the main kernel
 
-	  For more details see Documentation/kdump/kdump.rst
+	  For more details see Documentation/admin-guide/kdump/kdump.rst
 
 config AUTO_ZRELADDR
 	bool "Auto calculation of the decompressed kernel image address"