Add v1.8.0 changelog entry with February 2025 updates (#348)

* docs: add v1.8.0 changelog with features since v1.7.0

Adds changelog entry covering webhooks, Python SDK, Contact Books API,
email retention/cleanup, idempotency support, and various improvements.

https://claude.ai/code/session_012hGggJSKqRZB4PkaaPAyrS

* update

---------

Co-authored-by: Claude <noreply@anthropic.com>

apps/docs/changelog.mdx

@@ -3,17 +3,44 @@ title: "Changelog"
 description: "Product updates and announcements from Unsend"
 ---
 
-<Update label="October 2024" description="v1.7.0">
-
+<Update label="February 2025" description="v1.8.0">
 
 <Frame>
-    <img src="/images/changelog/schedule-campaign.png" alt="Schedule Campaigns" />
+  <img src="/images/changelog/webhook.png" alt="Schedule Campaigns" />
+</Frame>
+
+### Webhooks
+
+You can now receive real-time notifications for email events via webhooks. Configure webhook endpoints to track deliveries, bounces, complaints, and more. [Learn more](http://localhost:3000/guides/webhooks)
+
+### Contact Books API
+
+Manage your contact books programmatically with the new public API. Create, update, and organize contacts at scale.
+
+### Idempotency Support
+
+API requests now support idempotency keys, ensuring safe retries without duplicate sends.
+
+### Other improvements
+
+- Export contact books to CSV for offline use.
+- Security fixes for CVE-2025-55184 and CVE-2025-55183.
+- Various bug fixes and performance improvements.
+
+</Update>
+
+<Update label="October 2024" description="v1.7.0">
+
+<Frame>
+  <img src="/images/changelog/schedule-campaign.png" alt="Schedule Campaigns" />
 </Frame>
 
 ### Schedule Campaigns
+
 You can now Schedule campaigns with natural language like "tomorrow at 9am" or "next Monday at 10am".
 
 ### Campaigns API
+
 We're doubling down on APIs. Now you can create, schedule campaign emails from API. check [API documentation](/api-reference/introduction)
 
 ### Other improvements
@@ -30,9 +57,11 @@ We're doubling down on APIs. Now you can create, schedule campaign emails from A
 </Frame>
 
 ### Suppression List
+
 Hard bounce and complained email addresses are automatically added to the suppression list. Works for both transactional and marketing emails.
 
 ### Rebranding to useSend
+
 From now on we [useSend](https://usesend.com). Make sure to update your docker image and sdks.
 
 </Update>