update gmail.md to add warning about ratelimits (#321)

Co-authored-by: illy <[email protected]>
Co-authored-by: missytake <[email protected]>

Author: 3 people

_providers/gmail.md

@@ -17,7 +17,7 @@ server:
 opt:
   delete_to_trash: true
 before_login_hint: |
-  For Gmail accounts, you need to have "2-Step Verification" enabled and create an app-password.
+  For Gmail accounts, you need to have "2-Step Verification" enabled and create an app-password. Gmail limits how many messages you can send per day.
 last_checked: 2024-08
 website: https://gmail.com
 ---