fix: add possible values for "deletion_policy" (#983)

Author: muffl0n

README.md

@@ -137,7 +137,7 @@ determining that location is as follows:
 | create\_project\_sa | Whether the default service account for the project shall be created | `bool` | `true` | no |
 | default\_network\_tier | Default Network Service Tier for resources created in this project. If unset, the value will not be modified. See https://cloud.google.com/network-tiers/docs/using-network-service-tiers and https://cloud.google.com/network-tiers. | `string` | `""` | no |
 | default\_service\_account | Project default service account setting: can be one of `delete`, `deprivilege`, `disable`, or `keep`. | `string` | `"disable"` | no |
-| deletion\_policy | The deletion policy for the project. | `string` | `"PREVENT"` | no |
+| deletion\_policy | The deletion policy for the project. Possible values are: DELETE, PREVENT | `string` | `"PREVENT"` | no |
 | disable\_dependent\_services | Whether services that are enabled and which depend on this service should also be disabled when this service is destroyed. | `bool` | `true` | no |
 | disable\_services\_on\_destroy | Whether project services will be disabled when the resources are destroyed | `bool` | `true` | no |
 | domain | The domain name (optional). | `string` | `""` | no |

variables.tf

@@ -367,7 +367,7 @@ variable "cloud_armor_tier" {
 }
 
 variable "deletion_policy" {
-  description = "The deletion policy for the project."
+  description = "The deletion policy for the project. Possible values are: DELETE, PREVENT"
   type        = string
   default     = "PREVENT"
 }