Its been introduced by CISCO On November 19, 2015, system which helps cloud computing to reduce the response time from cloud computing to send-receive the information.
i think as it is more like a product/Concept might be the reason not so known. I am just writing this to make sure we understand the concept.
if cloud computing has faster response for send and received information. we may not required to have it.
This is my understanding.
Reference:
https://en.wikipedia.org/wiki/Fog_computing
Vinay Thakur 