[ADD] point_of_sale: How to handle kitchen & bar order printing?

https://docs.google.com/document/d/1R04CrrFaEgbeAGA6JZwHqHMU3ob5tKZX7HCFI7f4EHg/edit#

point_of_sale/restaurant/print.rst

@@ -1,3 +1,72 @@
 ===========================================
 How to handle kitchen & bar order printing?
-===========================================
+===========================================
+
+Configuration
+=============
+
+From the dashboard click on :menuselection:`More --> Settings`:
+
+.. image:: media/print01.png
+    :align: center
+
+Under the **Bar & Restaurant** section, tick **Bill Printing**.
+
+.. image:: media/print02.png
+    :align: center
+
+In order printers, click on **add an item** and then **Create**.
+
+.. image:: media/print03.png
+    :align: center
+
+Set a printer **Name**, its **IP address** and the **Category** 
+of product you want to print on this printer. The category 
+of product is useful to print the order for the kitchen.
+
+.. image:: media/print04.png
+    :align: center
+
+Several printers can be added this way
+
+.. image:: media/print05.png
+    :align: center
+
+Now when you register an order, products will be automatically
+printed on the correct printer.
+
+Print a bill before the payment
+===============================
+
+On the main screen, click on the **Bill** button.
+
+.. image:: media/print06.png
+    :align: center
+
+Finally click on **Print**.
+
+.. image:: media/print07.png
+    :align: center
+
+Click on **Ok** once it is done.
+
+Print the order (kitchen printing)
+==================================
+
+This is different than printing the bill. It only prints the list of the
+items.
+
+Click on **Order**, it will automatically be printed.
+
+.. image:: media/print08.png
+    :align: center
+
+.. note::
+    The printer is automatically chosen according to the products
+    categories set on it.
+
+.. seealso::
+    * :doc:`../shop/cash_control`
+    * :doc:`../shop/invoice`
+    * :doc:`../shop/refund`
+    * :doc:`../shop/seasonal_discount`