Update blueprints docs with correct listener example
Update blueprints docs with correct listener example

ashleysommer/sanic,Tim-Erwin/sanic,jrocketfingers/sanic,jrocketfingers/sanic,lixxu/sanic,Tim-Erwin/sanic,lixxu/sanic,lixxu/sanic,ai0/sanic,r0fls/sanic,channelcat/sanic,channelcat/sanic,r0fls/sanic,channelcat/sanic,ashleysommer/sanic,yunstanford/sanic,yunstanford/sanic,yunstanford/sanic,ashleysommer/sanic,lixxu/sanic,yunstanford/sanic,channelcat/sanic,ai0/sanic