Small changes to the readme (claranet#52)

Author: rednap

README.md

@@ -47,8 +47,8 @@ module "lambda" {
   }
 
   // Add environment variables.
-  environment {
-    variables {
+  environment = {
+    variables = {
       SLACK_URL = var.slack_url
     }
   }

lambda.tf

@@ -47,4 +47,4 @@ resource "aws_lambda_function" "lambda" {
       subnet_ids         = vpc_config.value.subnet_ids
     }
   }
-}
+}