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>
diff --git a/Documentation/filesystems/locks.txt b/Documentation/filesystems/locks.txt
index 2cf8108..5368690 100644
--- a/Documentation/filesystems/locks.txt
+++ b/Documentation/filesystems/locks.txt
@@ -19,7 +19,7 @@
 
 This should not cause problems for anybody, since everybody using a
 2.1.x kernel should have updated their C library to a suitable version
-anyway (see the file "Documentation/Changes".)
+anyway (see the file "Documentation/process/changes.rst".)
 
 1.2 Allow Mixed Locks Again
 ---------------------------
diff --git a/Documentation/filesystems/nfs/nfsroot.txt b/Documentation/filesystems/nfs/nfsroot.txt
index 0b2883b..5efae00 100644
--- a/Documentation/filesystems/nfs/nfsroot.txt
+++ b/Documentation/filesystems/nfs/nfsroot.txt
@@ -11,7 +11,7 @@
 In order to use a diskless system, such as an X-terminal or printer server
 for example, it is necessary for the root filesystem to be present on a
 non-disk device. This may be an initramfs (see Documentation/filesystems/
-ramfs-rootfs-initramfs.txt), a ramdisk (see Documentation/initrd.txt) or a
+ramfs-rootfs-initramfs.txt), a ramdisk (see Documentation/admin-guide/initrd.rst) or a
 filesystem mounted via NFS. The following text describes on how to use NFS
 for the root filesystem. For the rest of this text 'client' means the
 diskless system, and 'server' means the NFS server.
@@ -284,7 +284,7 @@
 	"kernel <relative-path-below /tftpboot>". The nfsroot parameters
 	are passed to the kernel by adding them to the "append" line.
 	It is common to use serial console in conjunction with pxeliunx,
-	see Documentation/serial-console.txt for more information.
+	see Documentation/admin-guide/serial-console.rst for more information.
 
 	For more information on isolinux, including how to create bootdisks
 	for prebuilt kernels, see http://syslinux.zytor.com/