[ADD] point_of_sale: How to manage multiple cashiers?

https://docs.google.com/document/d/1HttoILrB7mzpEYWSHbzzG4ZrpTOv25oce_5jpZN3ENk/edit#

point_of_sale/advanced/multi_cashiers.rst

@@ -1,3 +1,174 @@
 ================================
 How to manage multiple cashiers?
 ================================
+
+This tutorial will describe how to manage multiple cashiers. There are
+four differents ways to manage several cashiers.
+
+Switch cashier without any security
+===================================
+
+As prerequisite, you just need to have a second user with the **Point of
+Sale User** rights (Under the :menuselection:`General Settings --> Users` menu).
+On the **Dashboard** click on **New Session** as the main user.
+
+.. image:: media/multi_cashier01.png
+    :align: center
+
+On the top of the screen click on the **user name**.
+
+.. image:: media/multi_cashier02.png
+    :align: center
+
+And switch to another cashier.
+
+.. image:: media/multi_cashier03.png
+    :align: center
+
+The name on the top has changed which means you have changed the cashier.
+
+.. image:: media/multi_cashier04.png
+    :align: center
+
+Switch cashier with pin code
+============================
+
+Configuration
+-------------
+
+If you want your cashiers to need a pin code to be able to use it, you
+can set it up in by clicking on **Settings**.
+
+.. image:: media/multi_cashier05.png
+    :align: center
+
+Then click on **Manage access rights**.
+
+.. image:: media/multi_cashier06.png
+    :align: center
+
+**Edit** the cashier and add a security pin code on the **Point of Sale**
+tab.
+
+.. image:: media/multi_cashier07.png
+    :align: center
+
+Change cashier
+--------------
+
+On the **Dashboard** click on **New Session**.
+
+.. image:: media/multi_cashier08.png
+    :align: center
+
+On the top of the screen click on the **user name**.
+
+.. image:: media/multi_cashier09.png
+    :align: center
+
+Choose your **cashier**:
+
+.. image:: media/multi_cashier10.png
+    :align: center
+
+You will have to insert the user's **pin code** to be able to continue.
+
+.. image:: media/multi_cashier11.png
+    :align: center
+
+Now you can see that the cashier has changed.
+
+.. image:: media/multi_cashier12.png
+    :align: center
+
+Switch cashier with cashier barcode badge
+=========================================
+
+Configuration
+-------------
+
+If you want your cashiers to scan its badge, 
+you can set it up in by clicking on **Settings**.
+
+.. image:: media/multi_cashier13.png
+    :align: center
+
+Then click on **Manage access rights**
+
+.. image:: media/multi_cashier14.png
+    :align: center
+
+**Edit** the cashier and add a **security pin code** on the **Point of Sale**
+tab.
+
+.. image:: media/multi_cashier15.png
+    :align: center
+
+.. tip::
+    Be careful of the barcode nomenclature, the default one forced you
+    to use a barcode starting with ``041`` for cashier barcodes. To change that
+    go to :menuselection:`Point of Sale --> Configuration --> Barcode Nomenclatures`.
+
+.. image:: media/multi_cashier16.png
+    :align: center
+
+Change Cashier
+--------------
+
+On the **Dashboard** click on **New Session**.
+
+.. image:: media/multi_cashier17.png
+    :align: center
+
+On the top of the screen click on the **user name**.
+
+.. image:: media/multi_cashier18.png
+    :align: center
+
+When the cashier scans his own badge, you can see on the top that the
+cashier has changed.
+
+Assign session to a user
+========================
+
+Click on the menu :menuselection:`Point of Sale --> Orders --> Sessions`.
+
+.. image:: media/multi_cashier19.png
+    :align: center
+
+Then, click on **New** and assign as **Responsible** the correct cashier to the
+point of sale.
+
+.. image:: media/multi_cashier20.png
+    :align: center
+
+When the cashier logs in he is able to open the session
+
+.. image:: media/multi_cashier21.png
+    :align: center
+
+Assign a default point of sale to a cashier
+===========================================
+
+If you want your cashiers to be assigned to a point of sale, go to
+:menuselection:`Point of Sales --> Configuration --> Settings`.
+
+.. image:: media/multi_cashier22.png
+    :align: center
+
+Then click on **Manage Access Rights**.
+
+.. image:: media/multi_cashier23.png
+    :align: center
+
+**Edit** the cashier and add a **Default Point of Sale** under the **Point of
+Sale** tab.
+
+.. image:: media/multi_cashier24.png
+    :align: center
+
+.. seealso::
+    * :doc:`../shop/cash_control`
+    * :doc:`../shop/invoice`
+    * :doc:`../shop/refund`
+    * :doc:`../shop/seasonal_discount`