docs: repair broken references

In two different places, we are not making a cross-reference to some
resource correctly.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20201009161558.107041-2-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

docs/devel/multi-thread-tcg.rst

@@ -267,7 +267,7 @@ of view of external observers (e.g. another processor core). They can
 apply to any memory operations as well as just loads or stores.
 
 The Linux kernel has an excellent `write-up
-<https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/plain/Documentation/memory-barriers.txt>`
+<https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/plain/Documentation/memory-barriers.txt>`_
 on the various forms of memory barrier and the guarantees they can
 provide.
 

docs/devel/testing.rst

@@ -953,7 +953,7 @@ compiler flags are needed to build for a given target.
 If you have the ability to run containers as the user you can also
 take advantage of the build systems "Docker" support. It will then use
 containers to build any test case for an enabled guest where there is
-no system compiler available. See :ref: `_docker-ref` for details.
+no system compiler available. See :ref:`docker-ref` for details.
 
 Running subset of tests
 -----------------------