Azure waf custom terraform configuration is throwing error for match_variables

I'm adding waf configuration to avoid when ever "--BEGIN PUBLIC KEY---" is matching but terraform is throwing error about some required options

  name                = "example-wafpolicy"
  resource_group_name = azurerm_resource_group.rg.name
  location            = "Global"

  custom_rules {
    name     = "MatchPublicKey"
    priority = 1
    rule_type = "MatchRule"
    action   = "Block"

    match_conditions {
      match_variable = "RequestBody"
      operator       = "RegexMatch"
      match_values   = ["--BEGIN PUBLIC KEY---"]
    }
  }

  managed_rules {
    managed_rule_set {
      version = "1.1"
    }
  }
}```

```Too few blocks specified for "match_variables": At least 1 block(s) are expected for "match_variables"Terraform
Unexpected attribute: An attribute named "match_variable" is not expected hereTerraform

https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/cdn_frontdoor_firewall_policy

need follow this doc for the solution.

resource "azurerm_cdn_frontdoor_firewall_policy" "example" 

is the correct resource to use