In the documentation for config databases in sharded clusters, there are two examples where one is missing the replset name:

https://docs.mongodb.com/manual/reference/config-database/#config.shards

{ "_id" : "shard0000", "host" : "shard1/localhost:30000" }

and

{ "_id" : "shard0001", "host" : "localhost:30001", "tags": [ "NYC" ] }

I believe the 2nd example should continue to list the replset name like the 1st one, like so:

{ "_id" : "shard0001", "host" : "shard1/localhost:30001", "tags": [ "NYC" ] }

Thanks.