[ADD] payment_providers: add documentation for Toss Payments

- Introduction to Toss Payments and the specific payment methods supported in Odoo (Easy Payment, Bank Transfer, and Mobile Payment)
- Step-by-step instructions for configuration on the Toss Payments Merchant Portal, including accessing the Developer Center, retrieving the Client and Secret keys, and setting up the Webhook.
- Instructions for enabling and configuring the provider within Odoo.

closes odoo/documentation#16574

Signed-off-by: Kim Dohyun (kido) <kido@odoo.com>

content/applications/finance/payment_providers.rst

@@ -24,6 +24,7 @@ Online payments
    payment_providers/razorpay
    payment_providers/redsys
    payment_providers/stripe
+   payment_providers/tosspayments
    payment_providers/worldline
    payment_providers/xendit
    payment_providers/bank_payments
@@ -168,6 +169,12 @@ Online payment providers
      - Full only
      - Full and partial
      - |V|
+   * - :doc:`Toss Payments <payment_providers/tosspayments>`
+     - Odoo
+     -
+     -
+     -
+     -
    * - :doc:`Worldline <payment_providers/worldline>`
      - The provider's website
      - |V|
@@ -516,6 +523,7 @@ payments from other payments.
    - :doc:`payment_providers/razorpay`
    - :doc:`payment_providers/redsys`
    - :doc:`payment_providers/stripe`
+   - :doc:`payment_providers/tosspayments`
    - :doc:`payment_providers/worldline`
    - :doc:`payment_providers/xendit`
    - :doc:`payment_providers/bank_payments`

content/applications/finance/payment_providers/tosspayments.rst

@@ -0,0 +1,55 @@
+=============
+Toss Payments
+=============
+
+`Toss Payments <https://www.tosspayments.com>`_ is a South Korean payment solution provider.
+It allows businesses to accept a wide variety of local payment methods.
+
+.. _payment_providers/toss_payments/configure_dashboard:
+
+Configuration on the Toss Payments Merchant Portal
+==================================================
+
+#. `Create an account <https://app.tosspayments.com/signup>`_ on the Toss Payments Portal.
+#. `Apply for Service
+   <https://onboarding.tosspayments.com/registration/business-registration-number/>`_. Odoo
+   supports the following payment methods for Toss Payments under the `Basic Payment Package
+   <https://www.tosspayments.com/services>`_.
+
+   * `Easy Payment <https://docs.tosspayments.com/resources/glossary/easypay>`_
+   * `Bank Transfer <https://docs.tosspayments.com/resources/glossary/transfer-payment>`_
+   * `Mobile Payment <https://docs.tosspayments.com/resources/glossary/mobile-payment>`_
+
+#. Once approved, `log into the Merchant Portal <https://app.tosspayments.com/signin>`_ and click
+   :guilabel:`Developer Center` to access the developer center portal.
+#. Select the :guilabel:`Merchant ID` and navigate to the :guilabel:`API Key` menu.
+#. In the :guilabel:`API Individual Integration Key` section, copy the :guilabel:`Client Key` and
+   :guilabel:`Secret Key`, and save them for the :ref:`Odoo configuration step
+   <payment_providers/toss_payments/configure_odoo>`.
+#. Navigate to the :guilabel:`Webhook` menu and click :guilabel:`Register Webhook`.
+#. Enter a name to help identify the webhook.
+#. In the :guilabel:`URL` field, enter your Odoo database's URL, followed by
+   `/payment/toss-payments/webhook` (e.g.,
+   `https://example.odoo.com/payment/toss-payments/webhook`).
+
+   .. tip::
+       You can also copy the :guilabel:`Webhook URL` from the Toss Payments form in Odoo and paste
+       it.
+
+#. Ensure the :guilabel:`PAYMENT_STATUS_CHANGED` event is enabled, then save the webhook
+   settings.
+
+.. _payment_providers/toss_payments/configure_odoo:
+
+Configuration on Odoo
+=====================
+
+#. :ref:`Navigate to the payment provider Toss Payments <payment_providers/add_new>`.
+#. Fill in the :guilabel:`Client Key` and :guilabel:`Secret Key` fields with the information
+   saved at the step :ref:`payment_providers/toss_payments/configure_dashboard`.
+#. Configure the remaining options as needed.
+#. Set the :guilabel:`State` field to :guilabel:`Enabled` (or :guilabel:`Test Mode` if you are
+   trying Toss Payments as a :ref:`test <payment_providers/test-mode>`).
+
+.. seealso::
+   :doc:`../payment_providers`