Update documentation (#1926)

Update expansion documentation to consider the correct `kubectl minio` flags

docs/expansion.md

@@ -6,13 +6,13 @@ MinIO expansion is done in terms of MinIO pools, read more about the design in [
 
 ## Getting Started
 
-You can add capacity to the tenant using `kubectl minio` plugin.
+You can add capacity to the tenant using `kubectl minio` plugin, or using the MinIO Operator Console.
 
 ```
-kubectl minio tenant volume add --name TENANT_NAME --servers SERVERS --volumes TOTAL_VOLUMES --capacity TOTAL_RAW_CAPACITY
+kubectl minio tenant expand TENANT_NAME --servers SERVERS --volumes TOTAL_VOLUMES --capacity TOTAL_RAW_CAPACITY
 ```
 
-Remember to replace `TENANT_NAME` with tenant name where you want to add volumes, `SERVERS` with new servers to be added to the tenant, `TOTAL_VOLUMES` with total new volumes to be added to tenant and `TOTAL_RAW_CAPACITY` with total new raw capacity to be added to the tenant.
+Remember to replace `TENANT_NAME` with tenant name where you want to add volumes, `SERVERS` with the number of servers to be added to the tenant, `TOTAL_VOLUMES` with the total number of volumes to be added to tenant and `TOTAL_RAW_CAPACITY` with the total raw capacity to be added to the tenant.
 
 **NOTE**: Important points to consider _before_ using Tenant expansion:
 
@@ -24,17 +24,17 @@ Remember to replace `TENANT_NAME` with tenant name where you want to add volumes
 
 ### What are MinIO pools
 
-A MinIO pool is a self contained entity with same SLA's (read/write quorum) for each object. There are no limits on how many pools can be combined. After adding of a pool, MinIO simply uses the least used pool. All pools are for all purposes are invisible to an any application, and MinIO handles the pools internally. 
+A MinIO pool is a self-contained entity with same SLA's (read/write quorum) for each object. There are no limits on how many pools can be combined. After adding of a pool, MinIO simply uses the least used pool. All pools are for all purposes are invisible to an any application, and MinIO handles the pools internally. 
 
 ### Rules of Adding pools
 
-There is only one requirement, i.e. based on initial pool's erasure set count (say `n`), new pools are expected to have a minimum of `n` drives to match the original Tenant SLA or it should be in multiples of `n`. For example if initial set count is 4, new pools should have at least 4 or multiple of 4 drives.
+There is only one requirement, i.e. based on initial pool's erasure set count (say `n`), new pools are expected to have a minimum of `n` drives to match the original Tenant SLA, or it should be in multiples of `n`. For example if initial set count is 4, new pools should have at least 4 or multiple of 4 drives.
 
 ### Effects on KES/TLS Enabled Instance
 
 If your MinIO Operator configuration has [KES](https://github.com/minio/operator/blob/master/docs/kes.md) or [Automatic TLS](https://github.com/minio/operator/blob/master/docs/tls.md#automatic-csr-generation) enabled, there are additional considerations:
 
-- When new pools are added, Operator invalidates older self signed TLS certificates and the related secrets. Operator then creates new certificate signing requests (CSR). This is because there are new MinIO nodes that must be added in certificate DNS names. The administrator must approve these CSRs for MinIO server to be deployed again. Unless the CSR are approved, Operator will not create MinIO StatefulSet pods.
+- When new pools are added, Operator invalidates older self-signed TLS certificates and the related secrets. Operator then creates new certificate signing requests (CSR). This is because there are new MinIO nodes that must be added in certificate DNS names. The administrator must approve these CSRs for MinIO server to be deployed again. Unless the CSR are approved, Operator will not create MinIO StatefulSet pods.
 
 - If you're using your own certificates, as explained [here](https://github.com/minio/operator/blob/master/docs/tls.md#pass-certificate-secret-to-tenant), please ensure to use/update proper certificates that allow older and new MinIO nodes.