Added example in docs to create keys with expires
Added example in docs to create keys with expires

Closes #159

DynamicYield/ioredis,luin/ioredis,luin/ioredis,DynamicYield/ioredis,AVVS/ioredis,nswbmw/ioredis,mtlima/ioredis,xuyanxiang/ioredis,luin/ioredis