Document complement set operator "unless"
Document complement set operator "unless"

pdbogen/docs,chosenken/docs,tcolgate/docs,ddfreyne/prometheus-docs,ddfreyne/prometheus-docs,du2016/prometheus-docs,tcolgate/docs,Cepave/openfalcon.io,pdbogen/docs,chosenken/docs,prometheus/docs,prometheus/docs,open-falcon/open-falcon.github.io,du2016/prometheus-docs,prometheus/docs,open-falcon/open-falcon.github.io,tcolgate/docs,Cepave/openfalcon.io,ddfreyne/prometheus-docs,chosenken/docs,pdbogen/docs,open-falcon/open-falcon.github.io,Cepave/openfalcon.io,du2016/prometheus-docs,chosenken/docs,ddfreyne/prometheus-docs