overview page for whatsapp adaptor (#702)

* overview page for whatsapp adaptor

* Changed the property name for the bearer token to reflect what is in the config schema

* Changed the link to the correct WhatsApp business API page

---------

Co-authored-by: Pius Kariuki <[email protected]>

Author: aleksa-krolls

adaptors/whatsapp.md

@@ -0,0 +1,41 @@
+---
+title: WhatsApp Adaptor
+---
+
+## About WhatsApp
+
+The [WhatsApp Business Platform](https://developers.facebook.com/docs/whatsapp) enables organizations to communicate with their customers on WhatsApp at scale. It supports sending messages, notifications, and media, as well as receiving inbound customer messages through a secure and reliable API.
+
+This adaptor allows OpenFn users to integrate workflows with WhatsApp Business Cloud or On-Premise APIs to send and receive WhatsApp messages as part of automated processes.
+
+## Integration Options
+
+The WhatsApp Business API provides a [REST API](https://developers.facebook.com/docs/whatsapp) to manage message sending, conversations, and contacts. See [functions](/adaptors/packages/whatsapp-docs) for examples of how to use this adaptor to call the API.
+
+In addition, WhatsApp Business supports [Webhooks](https://developers.facebook.com/docs/whatsapp/cloud-api/webhooks/payload-examples) that deliver inbound messages and delivery status updates in real time. These can be consumed by OpenFn workflows via a [webhook event trigger](/documentation/build/triggers#webhook-event-triggers) when customers send messages.
+
+## Authentication
+Access to the WhatsApp Business API requires a `Permanent Access Token` (for Cloud API) or a generated `Bearer Token` (for On-Premise deployments). This token must be included as an Authorization Bearer Token in all requests.
+
+For Cloud API, you must also specify your `phone_number_id` and `whatsapp_business_account_id`.
+[See Meta WhatsApp Business docs](https://developers.facebook.com/docs/whatsapp/cloud-api/get-started) for detailed guidance.
+
+OpenFn users can use the `whatsapp` credential type when [creating a credential](/documentation/manage-projects/manage-credentials) on the app. 
+
+If working locally or if using a `Raw JSON` credential type in OpenFn, your configuration will look something like this ([see configuration docs](/adaptors/packages/whatsapp-configuration-schema)):
+
+```json
+{
+  "baseUrl": "https://graph.facebook.com/v21.0",
+  "apiToken": "EAAJZC...your_long_lived_access_token",
+  "phoneNumberId": "123456789012345",
+  "wabaId": "987654321098765"
+}
+
+```
+
+## Helpful Links
+
+- WhatsApp Business API documentation: https://developers.facebook.com/docs/whatsapp
+- Cloud API Get Started guide: https://developers.facebook.com/docs/whatsapp/cloud-api/get-started
+- Webhook payload examples: https://developers.facebook.com/docs/whatsapp/cloud-api/webhooks/payload-examples