help: Update notification related help pages as per new UI.

This commit updates the headings used in notification
related pages as per the updated headings after 14e383ad7a,
60112405ba, and 6651842dc.

templates/zerver/help/change-notification-sound.md

@@ -8,7 +8,7 @@ You can change the sound Zulip uses for audible desktop notifications.
 
 {settings_tab|notifications}
 
-1. Under **Other notification settings**, configure
+1. Under **Desktop message notifications**, configure
    **Notification sound**.
 
 {end_tabs}

templates/zerver/help/configure-message-notification-emails.md

@@ -9,7 +9,7 @@ name of the organization in the subject line of your message notification emails
 
 {settings_tab|notifications}
 
-1. Under **Other notification settings**, select
+1. Under **Email message notifications**, select
    **Include organization name in subject of message notification emails**.
 
 {end_tabs}
@@ -28,7 +28,7 @@ being sent through your email.
 
 {settings_tab|notifications}
 
-1. Under **Other notification settings**, toggle
+1. Under **Email message notifications**, toggle
    **Include message content in message notification emails**.
 
 {end_tabs}

templates/zerver/help/disable-new-login-emails.md

@@ -19,7 +19,7 @@ feel excessive.
 
 {settings_tab|notifications}
 
-1. Under **Other notification settings**, toggle
+1. Under **Other emails**, toggle
    **Send email notifications for new logins to my account**.
 
 {end_tabs}

templates/zerver/help/test-mobile-notifications.md

@@ -11,7 +11,7 @@ configured to send mobile notifications even when you're online.
 
 {settings_tab|notifications}
 
-1. Under **Other notification settings**, enable
+1. Under **Mobile message notifications**, enable
    **Send mobile notifications even if I'm online**.
 
 {end_tabs}