Update FormatTranslators README to include/direct how to generate .plc file？(Issue #26)

[RaidToRadar]

I wanted to bring up an old post as I do not see an instruction that enables the initial.plc to be generated and is required for google CT. Would anyone be able to help me or point me in the right direction to enable this, I have referenced issue #26 .

[RaidToRadar]

@ZhiangWang033 would you be able to share the code/function you have previously made to accomplish this, there does not seem to be any documentation or code relating to this enablement other than the issue discussed in #26. I would appreciate very much as I am trying to use it for my project.

[RaidToRadar]

After reading about more issues and other discussions, I realized that there is a script called gen_plc_from_pb.py in the directory /Flow/utils/. Perhaps maybe update the README to include this information or make a copy in the FormatTranslator src directory.