maintainers: Add docs/tracing.txt to Tracing

The topic of whether and by whom docs/tracing.txt is maintained was
brought up. It currently does not have an official maintainer.

Add it to the tracing section so that Stefan gets cc'ed on patches.

Signed-off-by: Andreas Färber <[email protected]>
Acked-by: Stefan Hajnoczi <[email protected]>
Cc: Peter Maydell <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>
diff --git a/MAINTAINERS b/MAINTAINERS
index d249947..f83d07c2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -548,6 +548,7 @@
 M: Stefan Hajnoczi <[email protected]>
 S: Maintained
 F: trace/
+F: docs/tracing.txt
 T: git://github.com/stefanha/qemu.git tracing
 
 Checkpatch