add server_builder_option
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index 11aaa37..26e808c 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -774,6 +774,7 @@
include/grpc++/impl/rpc_method.h \
include/grpc++/impl/rpc_service_method.h \
include/grpc++/impl/serialization_traits.h \
+include/grpc++/impl/server_builder_option.h \
include/grpc++/impl/service_type.h \
include/grpc++/impl/sync.h \
include/grpc++/impl/sync_cxx11.h \