docs/packet: Add api_key information

Signed-off-by: knrt10 <kautilya@kinvolk.io>

Author: knrt10

docs/configuration-reference/platforms/packet.md

@@ -29,6 +29,7 @@ Example configuration file:
 ```tf
 # mycluster.lokocfg
 variable "packet_token" {}
+variable "api_key" {}
 variable "asset_dir" {}
 variable "facility" {}
 variable "cluster_name" {}
@@ -65,6 +66,8 @@ backend "s3" {
 cluster "packet" {
   auth_token = var.packet_token
 
+  api_key = var.api_key
+
   asset_dir = var.asset_dir
 
   cluster_name = var.cluster_name
@@ -202,6 +205,7 @@ node_type = var.custom_default_worker_type
 | Argument                              | Description                                                                                                                                                                                                                                                                       |     Default     |     Type     | Required |
 |---------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|:---------------:|:------------:|:--------:|
 | `auth_token`                          | Packet Auth token. Use the `PACKET_AUTH_TOKEN` environment variable instead.                                                                                                                                                                                                      |        -        |    string    |  false   |
+| `api_key`                             | Packet API Key. This is needed for packet-ccm.                                                                                                                                                                                                                                    |        -        |    string    |   true   |
 | `asset_dir`                           | Location where Lokomotive stores cluster assets.                                                                                                                                                                                                                                  |        -        |    string    |   true   |
 | `cluster_name`                        | Name of the cluster.                                                                                                                                                                                                                                                              |        -        |    string    |   true   |
 | `tags`                                | List of tags that will be propagated to master nodes.                                                                                                                                                                                                                             |        -        | map(string)  |  false   |