[ADD] purchase: create a Rfq

Based on https://docs.google.com/document/d/1q2EQ3JfDi0RZ8fDaca9Ac67fnPj3ReLwJL-bRuQLeUM/edit#

purchase/purchases/rfq/create.rst

@@ -2,3 +2,79 @@
 How to create a Request for Quotation?
 ======================================
 
+A Request for Quotation (RfQ) is used when you plan to purchase some
+products and you would like to receive a quote for those products. In
+Odoo, the Request for Quotation is used to send your list of desired
+products to your supplier. Once your supplier has answered your request,
+you can choose to go ahead with the offer and purchase or to turn down
+the offer.
+
+For more information on best uses, please read the chapter :doc:`../../overview/difference`
+
+Configuration
+=============
+
+Creating a Request for Quotation
+--------------------------------
+
+In the Purchases module, open :menuselection:`Purchase --> Requests for Quotation`
+and click on **Create**.
+
+.. image:: ./media/image04.png
+	:align: center
+
+Select your supplier in the **Vendor** menu, or create it on-the-fly by
+clicking on **Create and Edit**. In the **Order Date** field, select
+the date to which you wish to proceed to the actual order.
+
+.. demo:fields:: purchase.purchase_rfq
+
+.. demo:action:: purchase.purchase_rfq
+
+   View *Request for Quotation* in our Online Demonstration
+
+In **Products**, click on Add an item. Select the product you wish to order
+in the **Product** menu. Specify the **Quantity** by inserting the
+number and selecting the unit of measure. In the **Unit Price** field,
+specify the price you would like to be offered (you can also leave the
+field blank if you don't know what the price should be) , and add the
+expected delivery date in the Scheduled Date field. Click on **Save**, then
+**Print Rfq** or **Send Rfq by email** (make sure an email address is specified
+for this supplier or enter a new one).
+
+
+
+.. image:: ./media/image08.png
+	:align: center
+
+After having clicked on **Send**, you will notice that the RFQ's status will
+switch from **Draft** to **RFQ Sent**.
+
+.. image:: ./media/image06.png
+	:align: center
+
+Once your supplier has replied with an offer, update the RfQ by clicking
+on **Edit** to fit the quotation (prices, taxes, expected delivery lead
+time, payment terms, etc.), then click on **Save** to issue a Purchase
+Order.
+
+To proceed with the order, click on **Confirm Order** to send the order to
+the supplier. The RfQ's status will switch to **Purchase Order**.
+
+.. image:: ./media/image11.png
+	:align: center
+
+The status of the RfQ will change to PURCHASE ORDER. Tabs in the upper
+right corner of the order will show 1 Shipment and 0 Invoice.
+
+.. image:: ./media/image10.png
+	:align: center
+
+.. seealso:: 
+
+	:doc:`../../overview/from_po_to_invoice`
+
+.. rst-class:: text-muted
+
+| Written by Samuel Cabodi (Odoo)
+| Proofread by Geoffrey Bressan (Odoo)