NIFI-5726 - Update README with Slack Workspace information
NIFI-5726 - Update README with Slack Workspace information

This closes #3093

Signed-off-by: Mike Thomsen <ca0fb807feba88baa8476b14928d102f26c2f6be@gmail.com>

m-hogue/nifi,mans2singh/nifi,mattyb149/nifi,bbende/nifi,pvillard31/nifi,patricker/nifi,bbende/nifi,aperepel/nifi,bbende/nifi,pvillard31/nifi,jfrazee/nifi,jfrazee/nifi,alopresto/nifi,peter-gergely-horvath/nifi,joewitt/incubator-nifi,peter-gergely-horvath/nifi,m-hogue/nifi,patricker/nifi,MikeThomsen/nifi,MikeThomsen/nifi,jskora/nifi,trixpan/nifi,jtstorck/nifi,jfrazee/nifi,mans2singh/nifi,mans2singh/nifi,mattyb149/nifi,alopresto/nifi,ijokarumawak/nifi,alopresto/nifi,patricker/nifi,mcgilman/nifi,joewitt/incubator-nifi,ijokarumawak/nifi,jtstorck/nifi,aperepel/nifi,mans2singh/nifi,peter-gergely-horvath/nifi,ijokarumawak/nifi,jtstorck/nifi,YolandaMDavis/nifi,apsaltis/nifi,aperepel/nifi,MikeThomsen/nifi,mcgilman/nifi,patricker/nifi,bbende/nifi,mcgilman/nifi,bbende/nifi,joewitt/incubator-nifi,pvillard31/nifi,jskora/nifi,peter-gergely-horvath/nifi,YolandaMDavis/nifi,pvillard31/nifi,patricker/nifi,mattyb149/nifi,MikeThomsen/nifi,aperepel/nifi,alopresto/nifi,jskora/nifi,jtstorck/nifi,trixpan/nifi,trixpan/nifi,mans2singh/nifi,pvillard31/nifi,ijokarumawak/nifi,mattyb149/nifi,jskora/nifi,mattyb149/nifi,m-hogue/nifi,YolandaMDavis/nifi,alopresto/nifi,ijokarumawak/nifi,apsaltis/nifi,pvillard31/nifi,pvillard31/nifi,jfrazee/nifi,YolandaMDavis/nifi,alopresto/nifi,bbende/nifi,ijokarumawak/nifi,m-hogue/nifi,apsaltis/nifi,jfrazee/nifi,peter-gergely-horvath/nifi,jfrazee/nifi,m-hogue/nifi,apsaltis/nifi,apsaltis/nifi,YolandaMDavis/nifi,jtstorck/nifi,jfrazee/nifi,joewitt/incubator-nifi,jtstorck/nifi,mattyb149/nifi,alopresto/nifi,jtstorck/nifi,patricker/nifi,YolandaMDavis/nifi,mcgilman/nifi,patricker/nifi,mans2singh/nifi,m-hogue/nifi,trixpan/nifi,peter-gergely-horvath/nifi,MikeThomsen/nifi,trixpan/nifi,MikeThomsen/nifi,pvillard31/nifi,jskora/nifi,m-hogue/nifi,jfrazee/nifi,apsaltis/nifi,mcgilman/nifi,YolandaMDavis/nifi,mcgilman/nifi,aperepel/nifi,joewitt/incubator-nifi,aperepel/nifi,jskora/nifi,mattyb149/nifi,mcgilman/nifi,joewitt/incubator-nifi,MikeThomsen/nifi,trixpan/nifi