Minor typo fixes

Signed-off-by: Tommy <[email protected]>

Author: TommyTran732

content/posts/linux/Slightly Improving Mailcow Security.md

@@ -30,17 +30,17 @@ smtpd_tls_mandatory_ciphers = high
 
 These security configurations can be added/modified in `data/conf/nginx/includes/site-defaults.conf`.
 
-## SSL Ciphers
+### SSL Ciphers
 
 Consider only supporting ciphers matching that of TLSv1.3:
 
 ```
 ssl_ciphers "ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256";
 ```
 
-## HSTS
+### HSTS
 
-Consider adding `includeSubDomains;`to the HSTS configuration if all of your services are using HTTPS:
+Consider adding `includeSubDomains;` and `preload;` to the HSTS configuration if all of your services are using HTTPS:
 
 ```
 add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload";