docs: Use reference to link to rst file

Current document includes the path to an RST doc file.  Since this is an
RST file we can make this a link.  Keeps the path as the link title
since that what the original author wrote.

Use reference to link to rst file.
Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/vm/numa.rst

@@ -109,8 +109,8 @@ System administrators and application designers can restrict a task's migration
 to improve NUMA locality using various CPU affinity command line interfaces,
 such as taskset(1) and numactl(1), and program interfaces such as
 sched_setaffinity(2).  Further, one can modify the kernel's default local
-allocation behavior using Linux NUMA memory policy.
-[see Documentation/admin-guide/mm/numa_memory_policy.rst.]
+allocation behavior using Linux NUMA memory policy. [see
+:ref:`Documentation/admin-guide/mm/numa_memory_policy.rst <numa_memory_policy>`].
 
 System administrators can restrict the CPUs and nodes' memories that a non-
 privileged user can specify in the scheduling or NUMA commands and functions