meta-google: Add ztai,nanzhou to owners and maintainers

Signed-off-by: Zhenfei Tai <ztai@google.com>
Change-Id: Iee9923313db08862a18eacb176d4be6c73373aed
diff --git a/meta-google/OWNERS b/meta-google/OWNERS
index 4a63ee6..44cdb49 100644
--- a/meta-google/OWNERS
+++ b/meta-google/OWNERS
@@ -5,3 +5,5 @@
 - edtanous@google.com
 - brandonkim@google.com
 - wltu@google.com
+- ztai@google.com
+- nanzhoumails@gmail.com