docs: fix broken documentation links

Mostly due to x86 and acpi conversion, several documentation
links are still pointing to the old file. Fix them.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/admin-guide/ras.rst b/Documentation/admin-guide/ras.rst
index c7495e4..2b20f5f 100644
--- a/Documentation/admin-guide/ras.rst
+++ b/Documentation/admin-guide/ras.rst
@@ -199,7 +199,7 @@
   mode).
 
 .. [#f3] For more details about the Machine Check Architecture (MCA),
-  please read Documentation/x86/x86_64/machinecheck at the Kernel tree.
+  please read Documentation/x86/x86_64/machinecheck.rst at the Kernel tree.
 
 EDAC - Error Detection And Correction
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