docs(account): restructure overview for new personal settings layout

Rename the "My Settings" section to "Personal settings" and link out to
the three new sub-pages (Profile, Security, Emails and notifications).
Update the intro and replace the dashboard screenshot to reflect the new
user menu dropdown.

DX-1074

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: matt423

src/images/content/screenshots/dash/account.png

@@ -31,3 +31,15 @@ View detailed [reports](https://ably.com/accounts/any/apps/any/reports) about yo
 ## Team <a id="team"/>
 
 [Manage the users](https://ably.com/accounts/any/account_users) that have access to your account. The account owner role has full permissions to manage the account, including adding and removing users, and managing their [roles](/docs/platform/account/team).
+
+## Personal settings <a id="personal"/>
+
+Click the user avatar in the top-right of the Ably dashboard to access your personal settings:
+
+![Ably user menu](../../../../images/content/screenshots/dash/account.png)
+
+Your personal settings are organized into three sections:
+
+* [Profile](https://ably.com/users/settings/profile): view and edit your name and email address, or delete your profile.
+* [Security](https://ably.com/users/settings/security): manage your password, [two-factor authentication (2FA)](/docs/platform/account/2fa), and connected login providers (Google, GitHub).
+* [Emails and notifications](https://ably.com/users/settings/emails_and_notifications): customize Ably email preferences (product updates, news, educational emails) and set up notifications for account usage.