Add docs for new operators introduced since 3.0.0
Add docs for new operators introduced since 3.0.0

`!in`, `!instanceof`, `?[]`, `?=`

shils/groovy,paulk-asert/groovy,paulk-asert/incubator-groovy,apache/incubator-groovy,armsargis/groovy,shils/groovy,armsargis/groovy,paulk-asert/groovy,apache/groovy,armsargis/groovy,paulk-asert/incubator-groovy,apache/groovy,apache/groovy,apache/groovy,paulk-asert/incubator-groovy,shils/incubator-groovy,armsargis/groovy,shils/groovy,shils/incubator-groovy,shils/incubator-groovy,apache/incubator-groovy,shils/groovy,paulk-asert/groovy,paulk-asert/groovy,apache/incubator-groovy,apache/incubator-groovy,paulk-asert/incubator-groovy,paulk-asert/incubator-groovy,shils/incubator-groovy