feat(rdb): improve documentation about migrate (#2485)

Co-authored-by: Rémy Léone <rleone@scaleway.com>

Author: scaleway-bot

cmd/scw/testdata/test-all-usage-redis-cluster-migrate-usage.golden

@@ -1,6 +1,6 @@
 🎲🎲🎲 EXIT CODE: 0 🎲🎲🎲
 🟥🟥🟥 STDERR️️ 🟥🟥🟥️
-Migrate a cluster.
+Upgrade your Database for Redis® cluster to a new version or scale it vertically / horizontally. Please note: scaling horizontally your Database for Redis® cluster will renew its TLS certificate.
 
 USAGE:
   scw redis cluster migrate <cluster-id ...> [arg=value ...]

cmd/scw/testdata/test-all-usage-redis-cluster-usage.golden

@@ -12,7 +12,7 @@ AVAILABLE COMMANDS:
   get-certificate   Get the TLS certificate of a cluster
   list              List clusters
   metrics           Get metrics of a cluster
-  migrate           Migrate a cluster
+  migrate           Migrate your cluster architecture
   renew-certificate Renew the TLS certificate of a cluster
   update            Update a cluster
 

docs/commands/redis.md

@@ -14,7 +14,7 @@ Managed Database for Redis™ API
   - [Get the TLS certificate of a cluster](#get-the-tls-certificate-of-a-cluster)
   - [List clusters](#list-clusters)
   - [Get metrics of a cluster](#get-metrics-of-a-cluster)
-  - [Migrate a cluster](#migrate-a-cluster)
+  - [Migrate your cluster architecture](#migrate-your-cluster-architecture)
   - [Renew the TLS certificate of a cluster](#renew-the-tls-certificate-of-a-cluster)
   - [Update a cluster](#update-a-cluster)
 - [Endpoints management commands](#endpoints-management-commands)
@@ -269,9 +269,9 @@ scw redis cluster metrics <cluster-id ...> [arg=value ...]
 
 
 
-### Migrate a cluster
+### Migrate your cluster architecture
 
-Migrate a cluster.
+Upgrade your Database for Redis® cluster to a new version or scale it vertically / horizontally. Please note: scaling horizontally your Database for Redis® cluster will renew its TLS certificate.
 
 **Usage:**
 

internal/namespaces/redis/v1alpha1/redis_cli.go

@@ -393,8 +393,8 @@ func redisClusterList() *core.Command {
 
 func redisClusterMigrate() *core.Command {
 	return &core.Command{
-		Short:     `Migrate a cluster`,
-		Long:      `Migrate a cluster.`,
+		Short:     `Migrate your cluster architecture`,
+		Long:      `Upgrade your Database for Redis® cluster to a new version or scale it vertically / horizontally. Please note: scaling horizontally your Database for Redis® cluster will renew its TLS certificate.`,
 		Namespace: "redis",
 		Resource:  "cluster",
 		Verb:      "migrate",