[ADD] accounting: add Vietnam localisations

Impacted Version:

- 16.4 and above

This commit improve below features:

- Vietnam accounting documentation
- Vietnamese QR banking code documentation

task-3344654

closes odoo/documentation#5043

Related: odoo/odoo#127689
Signed-off-by: Tommy Ng (tong) <tong@odoo.com>

content/applications/finance/fiscal_localizations.rst

@@ -124,7 +124,7 @@ available on Odoo.
 - United States - Accounting
 - Uruguay - Accounting
 - Venezuela - Accounting
-- Vietnam - Accounting
+- :doc:`Vietnam - Accounting <fiscal_localizations/vietnam>`
 
 .. toctree::
    :titlesonly:
@@ -151,5 +151,6 @@ available on Odoo.
    fiscal_localizations/singapore
    fiscal_localizations/spain
    fiscal_localizations/switzerland
+   fiscal_localizations/vietnam
    fiscal_localizations/united_arab_emirates
    fiscal_localizations/united_kingdom

content/applications/finance/fiscal_localizations/vietnam.rst

@@ -0,0 +1,55 @@
+=======
+Vietnam
+=======
+
+Add Vietnamese QR banking codes to invoices
+===========================================
+
+Vietnamese QR banking is a payment service platform that allows customers to make instant domestic
+payments to individuals and merchants in Vietnamese dong via online and mobile banking.
+
+Activate QR codes
+-----------------
+
+Go to :menuselection:`Accounting --> Configuration --> Settings`. Under the :guilabel:`Customer
+Payments` section, activate the :guilabel:`QR Codes` feature.
+
+Vietnamese QR banking bank account configuration
+------------------------------------------------
+
+Go to :menuselection:`Contacts --> Configuration --> Bank Accounts` and select the bank account for
+which you want to activate Vietnamese QR banking. Set the :guilabel:`Bank Identifier Code` on the
+bank. Then set the :guilabel:`Proxy Type` and fill in the :guilabel:`Proxy Value` field depending on
+the type you chose.
+
+.. important::
+   - The account holder's country must be set to Vietnam on its contact form.
+   - You could also include the invoice number in the QR code by checking the :guilabel:`Include
+     Reference` checkbox.
+
+.. image:: vietnam/vn-paynow-bank-setting.png
+   :alt: Vietnamese QR banking bank account configuration
+
+.. seealso::
+   :doc:`../accounting/bank`
+
+Bank journal configuration
+--------------------------
+
+Go to :menuselection:`Accounting --> Configuration --> Journals`, open the bank journal, then fill
+out the :guilabel:`Account Number` and :guilabel:`Bank` under the :guilabel:`Journal Entries` tab.
+
+.. image:: vietnam/vn-bank-account-journal-setting.png
+   :alt: Bank Account's journal configuration
+
+Issue invoices with Vietnamese QR banking QR codes
+--------------------------------------------------
+
+When creating a new invoice, open the :guilabel:`Other Info` tab and set the :guilabel:`Payment
+QR-code` option to *EMV Merchant-Presented QR-code*.
+
+.. image:: vietnam/vn-qr-code-invoice-setting.png
+   :alt: Select EMV Merchant-Presented QR-code option
+
+Ensure that the :guilabel:`Recipient Bank` is the one you configured, as Odoo uses this field to
+generate the Vietnamese QR banking QR code.