owners: add motomuman to core networking owners

Test: owners file change
Change-Id: I54290c2d039acb7281cc7311480793b037c60d4f
diff --git a/OWNERS_core_networking b/OWNERS_core_networking
index bc1d002..3a08422 100644
--- a/OWNERS_core_networking
+++ b/OWNERS_core_networking
@@ -10,6 +10,7 @@
 markchien@google.com
 martinwu@google.com
 maze@google.com
+motomuman@google.com
 nuccachen@google.com
 paulhu@google.com
 prohr@google.com