update cloudformation template to modify the sample env file, now that

all the config params are stored in environment variables as per commit
57286362ce

template.aws.yaml

@@ -143,8 +143,9 @@ Resources:
           yum install -y git
           git clone https://github.com/doccano/doccano.git
           cd doccano
-          sed -i s/"admin"/${Username}/g docker-compose.prod.yml
-          sed -i s/"password"/${Password}/g docker-compose.prod.yml
+          cp config/.env.example .env
+          sed -i s/admin/${Username}/g .env
+          sed -i s/password/${Password}/g .env
           docker-compose -f docker-compose.prod.yml up -d
       Tags:
         - Key: Name