notifications: Add help link for "Followed topics" in triggers table.

Previously, the Notification triggers table in Settings lacked a
direct link to documentation for 'Followed topics'.

This commit updates the AllNotifications type to include an optional
'help_link' field and adds conditional rendering in the template to
show the help icon only if 'help_link' is present.The corresponding
test has been updated to verify the presence of the help link.
This enables direct links to relevant docs, improving usability.

Fixes: #32033.

web/src/settings_config.ts

@@ -834,7 +834,11 @@ export function get_notifications_table_row_data(
 }
 
 export type AllNotifications = {
-    general_settings: {label: string; notification_settings: NotificationSettingCheckbox[]}[];
+    general_settings: {
+        label: string;
+        notification_settings: NotificationSettingCheckbox[];
+        help_link?: string;
+    }[];
     settings: {
         desktop_notification_settings: string[];
         mobile_notification_settings: string[];
@@ -870,6 +874,7 @@ export const all_notifications = (settings_object: Settings): AllNotifications =
                 followed_topic_notification_settings,
                 settings_object,
             ),
+            help_link: "/help/follow-a-topic",
         },
     ],
     settings: {

web/templates/settings/notification_settings.hbs

@@ -29,7 +29,12 @@
             <tbody>
                 {{#each general_settings}}
                     <tr>
-                        <td>{{ this.label }}</td>
+                        <td>
+                            {{ this.label }}
+                            {{#if this.help_link}}
+                                {{> ../help_link_widget link=this.help_link }}
+                            {{/if}}
+                        </td>
                         {{#each this.notification_settings}}
                             {{> notification_settings_checkboxes
                               setting_name=this.setting_name

web/tests/settings_config.test.cjs

@@ -119,6 +119,7 @@ run_test("all_notifications", ({override}) => {
         },
         {
             label: "translated: Followed topics",
+            help_link: "/help/follow-a-topic",
             notification_settings: [
                 {
                     is_checked: false,