docs: fix the readme test commands

Author: nfroidure

README.md

@@ -39,8 +39,7 @@ SMTP_CONNECTION_URL=smtp://localhost:2025 node --run dev -- sendMail --recipient
 # This should work with the appropriate token
 SMTP_CONNECTION_URL=smtp://localhost:2025 node --run dev -- sendMail --recipient text+$APPROPRIATE_TOKEN@enigma.com --sender test@xmp.com --subject test --message test
 
-SMTP_CONNECTION_URL=smtp://localhost:2025 node --run dev -- sendMail --recipient text@enigma.com --sender test@xmp.com --headers 
-'{"X-SafeSend-Token": "$APPROPRIATE_TOKEN"}' --subject test --message test
+SMTP_CONNECTION_URL=smtp://localhost:2025 node --run dev -- sendMail --recipient text@enigma.com --sender test@xmp.com --headers '{"X-SafeSend-Token": "$APPROPRIATE_TOKEN"}' --subject test --message test
 ```
 
 You can debug the token store anytime by running: