Adding sizing recommendations for file descriptors to the ops guide.
Author: Dustin Cote <dustin@confluent.io>
Author: Dustin Cote <dustin@dustins-mbp.attlocal.net>
Reviewers: Gwen Shapira
Closes#1353 from cotedm/KAFKA-3683 and squashes the following commits:
8120318 [Dustin Cote] Adding file descriptor sizing recommendations
0908aa9 [Dustin Cote] Merge https://github.com/apache/kafka into trunk
32315e4 [Dustin Cote] Merge branch 'trunk' of https://github.com/cotedm/kafka into trunk
13309ed [Dustin Cote] Update links for new consumer API
4dcffc1 [Dustin Cote] Update links for new consumer API
0e1c012fb5