docs: fix locations of several documents that got moved

The previous patch renamed several files that are cross-referenced
along the Kernel documentation. Adjust the links to point to
the right places.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/nvdimm/Kconfig

@@ -28,7 +28,7 @@ config BLK_DEV_PMEM
 	  non-standard OEM-specific E820 memory type (type-12, see
 	  CONFIG_X86_PMEM_LEGACY), or it is manually specified by the
 	  'memmap=nn[KMG]!ss[KMG]' kernel command line (see
-	  Documentation/kernel-parameters.txt).  This driver converts
+	  Documentation/admin-guide/kernel-parameters.rst).  This driver converts
 	  these persistent memory ranges into block devices that are
 	  capable of DAX (direct-access) file system mappings.  See
 	  Documentation/nvdimm/nvdimm.txt for more details.