grpc++.h was not installed
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index dfaeb43..bbd1706 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -766,6 +766,7 @@
 include/grpc++/create_channel.h \
 include/grpc++/generic/async_generic_service.h \
 include/grpc++/generic/generic_stub.h \
+include/grpc++/grpc++.h \
 include/grpc++/impl/call.h \
 include/grpc++/impl/client_unary_call.h \
 include/grpc++/impl/grpc_library.h \