Update maintainers to Audrow Nash (#26)

Signed-off-by: Scott K Logan <[email protected]>

package.xml

@@ -8,10 +8,12 @@
   <description>
     Wrapper around yaml-cpp, it provides a fixed CMake module and an ExternalProject build of it.
   </description>
-  <maintainer email="william@osrfoundation.org">William Woodall</maintainer>
+  <maintainer email="audrow@openrobotics.org">Audrow Nash</maintainer>
   <license>Apache License 2.0</license>  <!-- the contents of this package are Apache 2.0 -->
   <license>MIT</license>  <!-- yaml-cpp is MIT -->
 
+  <author email="[email protected]">William Woodall</author>
+
   <url type="website">https://github.com/jbeder/yaml-cpp</url>
 
   <buildtool_depend>ament_cmake</buildtool_depend>