Documentation about creating Sharded Keyspace should be clearer

[podoi17]

Reading the Documentation about sharded keyspace
https://vitess.io/docs/16.0/user-guides/vschema-guide/sharded/
leaves the impression that it is enough to create shards for a table when executing the json via
vtctldclient ApplyVSchema --vschema-file vschema_customer_sharded.json customer
But after "just" doing that and executing

mysql> use `customer:-80`;
Database changed
mysql> select * from customer;

the error of
ERROR 1105 (HY000): target: customer.-80.primary: no healthy tablet available for 'keyspace:"customer" shard:"-80" tablet_type:PRIMARY'
occurs.

All steps from the scripts (30X) are necessary to create shards. The documentation is clearly not saying that.

[Satarupa22-SD]

@mattlord can you please check the PR #1817. Please do let me know if any changes are needed.