[ADD] account: How to accept paypal payments on invoices?

https://docs.google.com/document/d/1mJ3haiYVcMJtaPCcBr6YBHpJtczHt6ZlyFAqAREb5SI/edit

accounting/receivables/customer_invoices/deferred_revenues.rst

@@ -45,6 +45,7 @@ From the Accounting application, go to the menu :menuselection:`Configuration --
 Revenues Types`.
 
 .. figure:: ./media/deffered01.png
+  :figclass: figure
   :align: center
 
   Example: 12 months maintenance contract

accounting/receivables/customer_payments/paypal.rst

@@ -1,3 +1,158 @@
 ==========================================
 How to accept paypal payments on invoices?
 ==========================================
+
+The "Paypal Payment Acquirer" module allows you to accept payments via
+paypal, for your sales orders, invoices, or online orders. As paypal
+accepts payments through credit cards (VISA, Mastercard, …), you will be
+able to process most payment methods.
+
+Paypal support two modes:
+
+- Paypal Merchant Account: the user is redirected to paypal to do the
+  payment (either with a credit card or a paypal account)
+
+- PayPal PayFlow Pro (S2S, Server 2 Server): the user is not redirected
+  to paypal and the payment can be done in the background. This
+  method is mostly used for subscription businesses where you need
+  to charge your customers periodically.
+
+As of today, Odoo only support the normal Paypal Merchant Account.
+
+Configuration
+=============
+
+Install the "PayPal Payment Acquirer" module
+--------------------------------------------
+
+Start by installing the **PayPal Payment Acquirer** module.
+
+Once the module is installed, you should see a new payment acquirer in
+the Setting application, menu "Payment Acquirers".
+
+.. image:: ./media/paypal01.png
+  :align: center
+
+By default, Paypal is configured to work in a test environment,
+out-of-the-box. It means you can already test the full order to payment
+flow with the paypal sandbox, without having to configure the next
+steps.
+
+Creating and configuring a PayPal merchant account
+--------------------------------------------------
+
+Create a basic Paypal account
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+a. Existing or newly created Personal Paypal account can be used.
+
+b. Or upgrade your account to Business account (merchant) if needed
+   
+.. figure:: ./media/paypal02.png
+  :figclass: figure
+  :align: center
+
+  Paypal Account Summary page
+
+Paypal Configuration
+^^^^^^^^^^^^^^^^^^^^
+
+1. Access "Seller preferences" menu from `PayPal website <https://www.paypal.com/myaccount/home>`__
+
+   .. image:: ./media/paypal03.png
+
+.. _WebsitePreferences:
+
+2. Access "Website preferences" and configure Auto Return
+
+   * **Database name**: yourcompany
+   * **Website URL**: https://yourcompany.odoo.com/
+   * **Return URL**: https://yourcompany.odoo.com/shop/confirmation
+
+   .. image:: ./media/paypal04.png
+   .. image:: ./media/paypal05.png
+
+   These settings will redirect your buyer to your web confirmation page.
+
+   .. image:: ./media/paypal06.png
+
+3. Access and edit Instant payment notifications settings - IPN
+
+   .. image:: ./media/paypal07.png
+   .. image:: ./media/paypal08.png
+
+   Example
+
+   - **Database name**: "yourcompany"
+   - **Website URL**: https://yourcompany.odoo.com/
+   - **Notification URL**: https://yourcompany.odoo.com/payment/paypal/ipn/
+
+   .. tip:: verify that your Notify URL uses the correct protocol (HTTP / HTTPS)
+
+4. Set the encoding to UTF-8 from the menu :menuselection:`Settings --> 
+   Language Encoding --> More Options --> More selling tools`
+
+   .. image:: ./media/paypal09.png
+   
+   .. image:: ./media/paypal10.png
+   
+   .. image:: ./media/paypal11.png
+   
+5. Record your Merchant Paypal ID (personal or business account
+   both will have it) it will be entered in Odoo backend :menuselection:`Paypal
+   Settings --> Account Options`.
+
+   .. image:: ./media/paypal12.png
+
+   .. image:: ./media/paypal13.png
+
+6. If you want your customers to be able to pay through Paypal
+   while not having a Paypal account- following setting "Paypal Account
+   Optional" needs to be set to **ON**. All users will be able to
+   choose Credit/debit card payment option - Paypal account not
+   required.
+
+   .. image:: ./media/paypal14.png
+
+Setup your Paypal Payment Acquirer account credentials in Odoo
+--------------------------------------------------------------
+
+* :menuselection:`Settings --> Payments --> Payment Acquirers --> Paypal`
+
+* **Paypal Email ID**: your paypal account email address
+
+* **Paypal Merchant ID**: ID retrieved at previous step
+
+.. image:: ./media/paypal15.png
+  :align: center
+
+.. todo:: section How to test an order
+
+Troubleshooting
+===============
+
+If your eCommerce customer gets this Error Message after completing
+Paypal payment instead of being redirected to your database:
+
+.. image:: ./media/paypal16.png
+  :align: center
+
+Verify the Auto Return URL you have `configured in Paypal <WebsitePreferences_>`_
+is correct and pointing to your own domain name.
+
+You can either:
+
+* Enter the correct return URL and activate Auto Return
+
+* or deactivate Auto Return and delete URL (this method will have an
+  extra click through Paypal in order to return to your ecommerce
+  page.)
+
+.. seealso::
+
+  * :doc:`credit_cards`
+
+.. rst-class:: text-muted
+
+| Written by Glen Babakhin (Odoo)
+| Proofread by Samuel Cabodi (Odoo)