[ADD] Sales: new doc about returns and refunds

Task Number: 2514789

closes odoo/documentation#1019

Signed-off-by: Antoine Vandevenne (anv) <anv@odoo.com>

content/applications/sales/sales/products_prices.rst

@@ -10,3 +10,4 @@ Products & Prices
    products_prices/products
    products_prices/taxes
    products_prices/prices
+   products_prices/returns.rst

content/applications/sales/sales/products_prices/returns.rst

@@ -0,0 +1,96 @@
+===========================
+Process returns and refunds
+===========================
+
+The :guilabel:`Sales` app provides two different ways to process returns based on whether an
+invoice has been sent or not.
+
+Before invoicing
+================
+
+Returns are completed using *Reverse Transfers* when a customer decides to return a product before
+an invoice has been sent or validated.
+
+.. note::
+   In order to use Reverse Transfers, the :guilabel:`Inventory` app must also be installed.
+
+To start a return, open the :guilabel:`Sales` app, navigate to the customer's sales order, and
+click on the :guilabel:`Delivery` smart button to open the associated delivery order.
+
+On the validated delivery order, click :guilabel:`Return` to open the :guilabel:`Reverse Transfer`
+pop-up window. By default, the :guilabel:`Quantity` matches the validated quantities from the
+delivery order. Update the quantities if necessary. Click on the trash icon next to a line item to
+remove it from the return.
+
+.. image:: returns/reverse-transfer-popup.png
+   :align: center
+   :alt: The "Reverse Transfer" pop-up window, to make a return before invoicing the customer.
+
+Next, click :guilabel:`Return` to confirm the return. This generates a new warehouse operation for
+the incoming returned product(s). Upon receiving the return, the warehouse team validates the
+warehouse operation. Then, on the original sales order, the :guilabel:`Delivered` quantity will
+reflect the difference between the initial validated quantities and the returned quantities.
+
+.. image:: returns/updated-sales-quantities.png
+   :align: center
+   :alt: The updated "Delivered" quantity on the sales order after the reverse transfer.
+
+When an invoice is created, the customer receives an invoice only for the products they are
+keeping.
+
+After invoicing
+===============
+
+Sometimes, customers return an item after they receive and/or pay for their invoice. In these
+cases, a return using only *Reverse Transfers* is impossible since validated or sent invoices
+cannot be changed. However, *Reverse Transfers* can be used in conjunction with *Credit Notes* to
+complete the customer's return.
+
+To start a return, navigate to the relevant sales order. If there is a payment registered on the
+sales order, then the payment details will appear in the Chatter, and the invoice (accessible
+through the :guilabel:`Invoices` smart button) will have a green banner across it.
+
+From the sales order, click on the :guilabel:`Delivery` smart button to view the validated delivery
+order. Then, click :guilabel:`Return` to open the :guilabel:`Reverse Transfer` pop-up window. Next,
+edit the :guilabel:`Product` or :guilabel:`Quantity` as needed for the return, and then click
+:guilabel:`Return`. This generates a new warehouse operation for the incoming returned product(s),
+which is validated by the warehouse team once the return is received. Then, on the sales order, the
+:guilabel:`Delivered` quantity will reflect the difference between the initial validated quantities
+and the returned quantities.
+
+Since the returned products have already been paid for, the validated invoice must be modified to
+reflect the return. Navigate to the relevant invoice (from the sales order, click on the
+:guilabel:`Invoices` smart button). Then, click on the :guilabel:`i` icon next to the
+:guilabel:`Paid` line at the bottom of the invoice to open the :guilabel:`Payment Info` window.
+Next, click :guilabel:`Unreconcile`.
+
+.. image:: returns/unreconcile-button.png
+   :align: center
+   :alt: The "Unreconcile" button.
+
+After the invoice is unreconciled, the options for :guilabel:`Send & Print` and
+:guilabel:`Register Payment` become available again alongside a note that there are outstanding
+payments for the customer.
+
+To process a refund, click :guilabel:`Add Credit Note` from the validated invoice.
+
+.. image:: returns/credit-note-popup.png
+   :align: center
+   :alt: The "Credit Note" pop-up window, to issue a credit to the customer after invoicing.
+
+Choose whether to issue a :guilabel:`Partial Refund`, :guilabel:`Full Refund`, or
+:guilabel:`Full refund and new draft invoice`. The :guilabel:`Partial Refund` option creates a
+draft credit note that can be edited before posting. The :guilabel:`Full refund and new draft
+invoice` option validates the credit note and duplicates the original invoice as a new draft.
+
+A :guilabel:`Reason` for the credit and a :guilabel:`Specific Journal` to use to process the credit
+can also be specified. If a :guilabel:`Specific Reversal Date` is selected, then a
+:guilabel:`Refund Date` must also be selected.
+
+After the information is filled, click :guilabel:`Reverse`. Then, for a :guilabel:`Partial Refund`
+or :guilabel:`Full refund and new draft invoice`, :guilabel:`Edit` the draft as needed, and
+finally, click :guilabel:`Confirm`.
+
+.. image:: returns/outstanding-payment-banner.png
+   :align: center
+   :alt: The "outstanding payments" banner.