docs/devel: fix grammar in multi-thread-tcg

Review comment came just too late ;-)

Signed-off-by: Alex Bennée <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Reviewed-by: Thomas Huth <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Message-Id: <[email protected]>

Author: stsquad

docs/devel/multi-thread-tcg.rst

@@ -107,7 +107,7 @@ including:
 
   - debugging operations (breakpoint insertion/removal)
   - some CPU helper functions
-  - linux-user spawning it's first thread
+  - linux-user spawning its first thread
 
 This is done with the async_safe_run_on_cpu() mechanism to ensure all
 vCPUs are quiescent when changes are being made to shared global