docs: fix broken paths to docs/devel/atomics.txt

With the move of some docs/ to docs/devel/ on ac06724a71,
a couple of references were not updated.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

docs/devel/lockcnt.txt

@@ -145,7 +145,7 @@ can also be more efficient in two ways:
 - on some platforms, one can implement QemuLockCnt to hold the lock
   and the mutex in a single word, making the fast path no more expensive
   than simply managing a counter using atomic operations (see
-  docs/atomics.txt).  This can be very helpful if concurrent access to
+  docs/devel/atomics.txt).  This can be very helpful if concurrent access to
   the data structure is expected to be rare.
 
 

include/qemu/atomic.h

@@ -8,7 +8,7 @@
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  *
- * See docs/atomics.txt for discussion about the guarantees each
+ * See docs/devel/atomics.txt for discussion about the guarantees each
  * atomic primitive is meant to provide.
  */
 
@@ -427,7 +427,7 @@
  * sequentially consistent operations.
  *
  * As long as they are used as paired operations they are safe to
- * use. See docs/atomic.txt for more discussion.
+ * use. See docs/devel/atomics.txt for more discussion.
  */
 
 #ifndef atomic_mb_read

tcg/README

@@ -446,7 +446,7 @@ when MTTCG is enabled.
 The guest translators should generate this opcode for all guest instructions
 which have ordering side effects.
 
-Please see docs/atomics.txt for more information on memory barriers.
+Please see docs/devel/atomics.txt for more information on memory barriers.
 
 ********* 64-bit guest on 32-bit host support