Add back print_operators_doc (#5970)

* add back print_operators_doc

* fix style check

* fix style check

Author: typhoonzero

paddle/operators/detail/send_recv.proto

@@ -32,4 +32,4 @@ message VariableMessage {
   bytes serialized = 2;
 }
 
-message VoidMessage {}
+message VoidMessage {}

paddle/scripts/docker/build.sh

@@ -183,6 +183,7 @@ EOF
     ${DOCKERFILE_GPU_ENV}
     ADD go/cmd/pserver/pserver /usr/bin/
     ADD go/cmd/master/master /usr/bin/
+    ADD paddle/pybind/print_operators_doc /usr/bin/
     # default command shows the paddle version and exit
     CMD ["paddle", "version"]
 EOF