[REM] accounting: Remove accounting/receivables/customer_invoices/modify_validated.html

Suppress this page : https://www.odoo.com/documentation/user/11.0/accounting/receivables/customer_invoices/modify_validated.html

It's repetitive with this one : https://www.odoo.com/documentation/user/11.0/accounting/receivables/customer_invoices/refund.html

accounting/receivables/customer_invoices.rst

@@ -12,4 +12,3 @@ Customer Invoices
    customer_invoices/installment_plans
    customer_invoices/deferred_revenues
    customer_invoices/refund
-   customer_invoices/modify_validated

accounting/receivables/customer_invoices/modify_validated.rst

@@ -1,50 +0,0 @@
-==================================
-How to modify a validated invoice?
-==================================
-
-In most accounting legislation over the word, it's not allowed to modify
-an invoice that is validated and sent to the customer. However, you
-sometimes need to change an invoice for different reasons: the sale has
-changed, the made a mistake while recording the invoice, etc.
-
-Thus, the right way to modify an invoice is to:
-
-1. Refund the original invoice
-2. Create a new invoice
-
-Odoo's refund mechanism helps you handle the whole process in just a few
-clicks.
-
-Modify an invoice
-=================
-
-If your invoice is still in draft, you can modify it the way you want.
-However, if your invoice is validated, you can not change it anymore. If
-you need to modify it, the right operations to do are:
-
-1. Refund the original invoice;
-2. Reconcile the original invoice with the refund to void them;
-3. Create a new draft invoice, a copy of the original;
-4. Validate the new invoice.
-
-All those steps are automated by Odoo. All you have to do is to click on
-the Refund button on an invoice.
-
-.. image:: ./media/modify01.png
-  :align: center
-
-In the refund dialog, select the option "Modify: create a refund,
-reconcile and create a draft invoice". Once you click on the "Create
-Refund" button, Odoo will void your existing invoice and create a new
-draft invoice that is a duplicate of the original one.
-
-Edit this new draft invoice and validate it when it's correct.
-
-.. note::
-
-	if you already sent the original invoice to your customer, you should send
-	the new invoice and the refund to the customer so that he gets all the documents.
-
-.. seealso::
-	
-	* :doc:`refund`