Add a default value for networks variable for flatten example

website/docs/language/functions/flatten.mdx

@@ -46,6 +46,38 @@ variable "networks" {
     cidr_block = string
     subnets    = map(object({ cidr_block = string }))
   }))
+  default = {
+    "private" = {
+      cidr_block = "10.1.0.0/16"
+      subnets = {
+        "db1" = {
+          cidr_block = "10.1.0.1/16"
+        }
+        "db2" = {
+          cidr_block = "10.1.0.2/16"
+        }
+      }
+    },
+    "public" = {
+      cidr_block = "10.1.1.0/16"
+      subnets = {
+        "webserver" = {
+          cidr_block = "10.1.1.1/16"
+        }
+        "email_server" = {
+          cidr_block = "10.1.1.2/16"
+        }
+      }
+    }
+    "dmz" = {
+      cidr_block = "10.1.2.0/16"
+      subnets = {
+        "firewall" = {
+          cidr_block = "10.1.2.1/16"
+        }
+      }
+    }
+  }
 }
 ```