Update usage section for kv-v1 docs (#5105)
Update usage section for kv-v1 docs (#5105)

While following along with the usage section in the kv-v1 docs I noticed this error.
Running the given command gives:

```text
$ vault kv list kv/my-secret
No value found at kv/my-secret/
```

Running `vault kv list kv/` gives the desired output. 

Also, I removed some trailing whitespace.
joelthompson/vault,quixoten/vault,hashicorp/vault,hartsock/vault,quixoten/vault,hartsock/vault,rnaveiras/vault,kingland/vault,rnaveiras/vault,kingland/vault,joelthompson/vault,kingland/vault,hartsock/vault,joelthompson/vault,hartsock/vault,rnaveiras/vault,kingland/vault,hartsock/vault,rnaveiras/vault,quixoten/vault,rnaveiras/vault,kingland/vault,joelthompson/vault,hashicorp/vault,hashicorp/vault,quixoten/vault,hashicorp/vault,hashicorp/vault,hashicorp/vault