NIFI-968 - add @OnPrimaryNodeStateChange to dev guide
NIFI-968 - add @OnPrimaryNodeStateChange to dev guide

This closes #2027.

Signed-off-by: Andy LoPresto <feb3cf00ee9bc01575e9428a4270e7b599f5a4bd@apache.org>

pvillard31/nifi,jjmeyer0/nifi,mattyb149/nifi,zhengsg/nifi,bbende/nifi,mattyb149/nifi,joetrite/nifi,mcgilman/nifi,mcgilman/nifi,michalklempa/nifi,jtstorck/nifi,michalklempa/nifi,aperepel/nifi,InspurUSA/nifi,mcgilman/nifi,peter-gergely-horvath/nifi,jfrazee/nifi,tijoparacka/nifi,zhengsg/nifi,alopresto/nifi,jfrazee/nifi,Wesley-Lawrence/nifi,dlukyanov/nifi,patricker/nifi,jjmeyer0/nifi,InspurUSA/nifi,patricker/nifi,jjmeyer0/nifi,YolandaMDavis/nifi,jfrazee/nifi,MikeThomsen/nifi,Wesley-Lawrence/nifi,tijoparacka/nifi,mcgilman/nifi,jjmeyer0/nifi,alopresto/nifi,trixpan/nifi,aperepel/nifi,trixpan/nifi,mattyb149/nifi,m-hogue/nifi,jtstorck/nifi,jfrazee/nifi,apsaltis/nifi,jtstorck/nifi,michalklempa/nifi,alopresto/nifi,pvillard31/nifi,dlukyanov/nifi,aperepel/nifi,InspurUSA/nifi,Xsixteen/nifi,mans2singh/nifi,mattyb149/nifi,InspurUSA/nifi,YolandaMDavis/nifi,MikeThomsen/nifi,ijokarumawak/nifi,Xsixteen/nifi,mans2singh/nifi,alopresto/nifi,dlukyanov/nifi,tijoparacka/nifi,zhengsg/nifi,joewitt/incubator-nifi,trixpan/nifi,jtstorck/nifi,joewitt/incubator-nifi,aperepel/nifi,pvillard31/nifi,patricker/nifi,mcgilman/nifi,alopresto/nifi,MikeThomsen/nifi,joetrite/nifi,m-hogue/nifi,jfrazee/nifi,Xsixteen/nifi,mattyb149/nifi,YolandaMDavis/nifi,jskora/nifi,tijoparacka/nifi,YolandaMDavis/nifi,ijokarumawak/nifi,dlukyanov/nifi,tijoparacka/nifi,pvillard31/nifi,Wesley-Lawrence/nifi,tijoparacka/nifi,peter-gergely-horvath/nifi,patricker/nifi,mattyb149/nifi,zhengsg/nifi,Xsixteen/nifi,jfrazee/nifi,YolandaMDavis/nifi,joetrite/nifi,trixpan/nifi,peter-gergely-horvath/nifi,jskora/nifi,mcgilman/nifi,joewitt/incubator-nifi,joetrite/nifi,jfrazee/nifi,apsaltis/nifi,joetrite/nifi,ijokarumawak/nifi,mcgilman/nifi,mans2singh/nifi,alopresto/nifi,mattyb149/nifi,jtstorck/nifi,joewitt/incubator-nifi,mans2singh/nifi,jjmeyer0/nifi,michalklempa/nifi,MikeThomsen/nifi,joewitt/incubator-nifi,InspurUSA/nifi,apsaltis/nifi,michalklempa/nifi,pvillard31/nifi,jfrazee/nifi,bbende/nifi,jtstorck/nifi,MikeThomsen/nifi,MikeThomsen/nifi,ijokarumawak/nifi,bbende/nifi,jskora/nifi,dlukyanov/nifi,bbende/nifi,mans2singh/nifi,patricker/nifi,trixpan/nifi,pvillard31/nifi,Wesley-Lawrence/nifi,m-hogue/nifi,jskora/nifi,m-hogue/nifi,mans2singh/nifi,InspurUSA/nifi,bbende/nifi,jtstorck/nifi,joetrite/nifi,jskora/nifi,bbende/nifi,patricker/nifi,zhengsg/nifi,pvillard31/nifi,joewitt/incubator-nifi,peter-gergely-horvath/nifi,YolandaMDavis/nifi,Wesley-Lawrence/nifi,apsaltis/nifi,patricker/nifi,m-hogue/nifi,trixpan/nifi,Wesley-Lawrence/nifi,m-hogue/nifi,MikeThomsen/nifi,michalklempa/nifi,aperepel/nifi,YolandaMDavis/nifi,ijokarumawak/nifi,pvillard31/nifi,peter-gergely-horvath/nifi,Xsixteen/nifi,alopresto/nifi,apsaltis/nifi,zhengsg/nifi,peter-gergely-horvath/nifi,Xsixteen/nifi,aperepel/nifi,apsaltis/nifi,m-hogue/nifi,jskora/nifi,ijokarumawak/nifi,jjmeyer0/nifi,dlukyanov/nifi