[ADD] eCommerce: checkout process page

Adding new page on checkout process for eCommerce. Forward to master.

closes odoo/documentation#3513

Taskid: 3110554
X-original-commit: 17ee191156
Signed-off-by: Aarab Tom (toaa) <toaa@odoo.com>

content/applications/websites/ecommerce/checkout_payment_shipping.rst

@@ -1,5 +1,3 @@
-:nosearch:
-
 ===============================
 Checkout, payment, and shipping
 ===============================
@@ -8,3 +6,4 @@ Checkout, payment, and shipping
    :titlesonly:
 
    checkout_payment_shipping/cart
+   checkout_payment_shipping/checkout

content/applications/websites/ecommerce/checkout_payment_shipping/checkout.rst

@@ -0,0 +1,128 @@
+========
+Checkout
+========
+
+You can customize the **checkout steps**, add more content using the **website builder**, and enable
+additional features such as **express checkout** and **sign in/up at checkout**.
+
+You can use **building blocks** to add content at any step of the checkout process. To do so, from
+any **checkout page**, go to :menuselection:`Edit --> Blocks`, and drag and drop **building blocks**
+to the page.
+
+.. note::
+   Note that content added through building blocks is **specific** to each step.
+
+Checkout steps
+==============
+
+Review order: promo code (and subtotal)
+---------------------------------------
+
+If you have enabled :guilabel:`Discounts, Loyalty, & Gift Card` in the settings
+(:menuselection:`Website --> Configuration --> Settings --> Shop - Products`), you can enable the
+:guilabel:`Promo Code` field (:menuselection:`Edit --> Customize`) from any checkout page. Customers
+can then redeem gift cards and promotional codes at the :guilabel:`Review Order` step.
+
+Furthermore, you can display the subtotal with discounts applied by enabling :guilabel:`Show
+Discount in Subtotal`.
+
+.. image:: checkout/checkout-subtotal.png
+   :align: center
+   :alt: Subtotal discount
+
+Address: B2B fields
+-------------------
+
+Optional :guilabel:`TIN/VAT` and :guilabel:`Company Name` fields can be added to the
+:guilabel:`Billing Address` form for B2B customers, at the :guilabel:`Address` step. To add the
+fields, go to :menuselection:`Edit --> Customize` from any checkout page, and enable
+:guilabel:`Show B2B fields`.
+
+Request extra info (additional step)
+------------------------------------
+
+You can request :guilabel:`Extra Info` from the customer by adding an :guilabel:`Extra Info` step
+between the :guilabel:`Address` and :guilabel:`Confirm Order` steps. To do so, go to
+:menuselection:`Edit --> Customize` from any checkout page, and enable :guilabel:`Extra Step
+Option`.
+
+.. image:: checkout/checkout-steps.png
+   :align: center
+   :alt: Checkout steps
+
+The :guilabel:`Extra Info` step is an online form linked to the quotation or sales order of the
+customer. The information added during that step can be found on the quotation or sales order of the
+customer from the back end, in the **Sales** app.
+
+When enabled, you can remove, add, and modify fields of the form by clicking on :guilabel:`Edit` in
+the top-right corner, and then clicking on any of the form's fields. All customization options, as
+well as the :guilabel:`+ Field` button to add new fields, are available at the bottom of the
+:guilabel:`Customize` menu under the :guilabel:`Field` section.
+
+.. image:: checkout/checkout-form.png
+   :align: center
+   :alt: Online form customization
+
+Confirm order: terms and conditions
+-----------------------------------
+
+You can ask customers to agree to the :guilabel:`Terms & Conditions` in order to confirm their order
+by enabling :guilabel:`Accept Terms & Conditions` under :menuselection:`Edit --> Customize` on any
+checkout page.
+
+.. image:: checkout/checkout-terms.png
+   :align: center
+   :alt: Terms and conditions
+
+Express checkout
+================
+
+You can enable a :guilabel:`Buy Now` button on products' pages which instantly takes the customer to
+the :guilabel:`Confirm Order` checkout page, instead of adding the product to the cart. To do so, go
+to :menuselection:`Website --> Configuration --> Settings --> Shop - Checkout Process section` and
+tick :guilabel:`Buy Now`. Alternatively, the :guilabel:`Buy Now` button can also be enabled from any
+product's page by going :menuselection:`Edit --> Customize`, in the :guilabel:`Cart` section.
+
+The button can be found next to the :guilabel:`Add to Cart` button on the product's page.
+
+.. image:: checkout/checkout-express.png
+   :align: center
+   :alt: Buy now (express checkout) button
+
+Guest and signed-in checkout
+============================
+
+It is possible to introduce a **checkout policy** under which customers can either checkout as
+**guests** or **signed-in users only**. Customers can also checkout as guest, and **optionally sign
+up later** in order to track their order, if enabled.
+
+To select a policy, go to :menuselection:`Website --> Configuration --> Settings --> Shop - Checkout
+Process`. You can choose between:
+
+- :guilabel:`Optional`: allows guests to checkout and later register from the **order confirmation**
+  email to track their order;
+- :guilabel:`Disabled (buy as guest)`: customers can only checkout as guests;
+- :guilabel:`Mandatory (no guest checkout)`: customers can only checkout if they have signed-in.
+
+B2B access restriction
+----------------------
+
+If you wish to restrict checkout only to **selected B2B customers**, enable :guilabel:`Mandatory (no
+guest checkout)` and go to :menuselection:`Website --> eCommerce --> Customers`. Select the customer
+you wish to **grant access to**, click :menuselection:`Action --> Grant portal access`, and click
+:guilabel:`Grant Access`.
+
+.. tip::
+   Settings are **website-specific**, which means you can set up a B2C website allowing **guest**
+   checkout, and another for B2B customers with **mandatory sign-in**.
+
+.. note::
+   Users can only have one portal access per **email**. They *cannot* be granted access to two
+   different portals with the same **email address**.
+
+Shared customer accounts
+------------------------
+
+If you enable :guilabel:`Shared Customer Accounts` under :menuselection:`Website --> Configuration
+--> Settings --> Privacy section`, you can allow or disallow access to *all* websites for one same
+account.