MAINTAINERS: Add an entry for the code of conduct

As I introduced these files, I'm willing to be the maintainer of them as
well.
Acked-by: Chris Mason <clm@fb.com>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -3681,6 +3681,12 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/media/coda.txt
 F:	drivers/media/platform/coda/
 
+CODE OF CONDUCT
+M:	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+S:	Supported
+F:	Documentation/process/code-of-conduct.rst
+F:	Documentation/process/code-of-conduct-interpretation.rst
+
 COMMON CLK FRAMEWORK
 M:	Michael Turquette <mturquette@baylibre.com>
 M:	Stephen Boyd <sboyd@kernel.org>