put batch size as well

infrastructure/terraform/lambda/ordnanceSurvey/variables.tf

@@ -23,6 +23,11 @@ variable "maximum_concurrency" {
   description = "Maximum number of concurrent Lambda invocations from SQS (2-1000). null = no limit."
 }
 
+variable "batch_size" {
+  type    = number
+  default = 1
+}
+
 locals {
   image_uri = "${var.ecr_repo_url}@${var.image_digest}"
 }