[problem of connecting lexicon or vocab to SDE tool] OOV doesn't show in wordstable
@vsl9 
Hi, 
Thank you very much for the great Speech Data Explorer (SDE) tool. I have faced a problem when connecting a simple lexicon (or vocab as the --vocab argument) to the SDE. My vocab file has just one word in each line and I have followed the SDE code and it can load it correctly. But the OOV words doesn't show in the `wordstable`. I think the problem is in [`update_wordstable`](https://github.com/NVIDIA/NeMo/blob/main/tools/speech_data_explorer/data_explorer.py#L495) method. Please help me to address this issue. 
I also send you a simple (my tmp) lexicon.  
Best
[lexicon.csv](https://github.com/NVIDIA/NeMo/files/7970171/lexicon.csv)

