Fix email description

Author: lorenyu

docs/infra/notifications.md

@@ -39,12 +39,12 @@ bin/terraform-init "infra/<APP_NAME>/service" "<ENVIRONMENT>"
 APPLICATION_ID="$(terraform -chdir=infra/<APP_NAME>/service output -raw pinpoint_app_id)"
 ```
 
-Then run the following command, replacing `<SENDER_EMAIL>` with the email address configured in notifications.tf (defaults to `notifications@<DOMAIN_NAME>`).:
+Then run the following command, replacing `<RECIPIENT_EMAIL>` with the email address you want to send to. Note that the sender email will be the email address configured in notifications.tf (defaults to `notifications@<DOMAIN_NAME>`):
 
 ```bash
 aws pinpoint send-messages --application-id "$APPLICATION_ID" --message-request '{
   "Addresses": {
-    "<SENDER_EMAIL>": { "ChannelType": "EMAIL" }
+    "<RECIPIENT_EMAIL>": { "ChannelType": "EMAIL" }
   },
   "MessageConfiguration": {
     "EmailMessage": {