[ADD] inventory: new doc about managing expiration dates

inventory/management/lots_serial_numbers.rst

@@ -8,4 +8,5 @@ Lots and Serial Numbers
 
    lots_serial_numbers/differences
    lots_serial_numbers/serial_numbers
-   lots_serial_numbers/lots
+   lots_serial_numbers/lots
+   lots_serial_numbers/expiration_dates

inventory/management/lots_serial_numbers/expiration_dates.rst

@@ -0,0 +1,66 @@
+=======================
+Manage expiration dates
+=======================
+
+In many companies, products have expiration dates and they should be
+tracked based on those dates. In the food industry, for example,
+tracking stocks based on expiration dates is mandatory to avoid selling
+expired products to customers.
+
+With Odoo, you can track your products based on their expiration dates,
+even if they are already tracked by lots or serial numbers.
+
+Configurations
+==============
+
+Application configuration
+-------------------------
+
+To use expiration dates tracking, open the *Inventory* application and
+go to *Configuration > Settings* and activate the *Lots & Serial
+Numbers* and *Expiration Dates* features.
+
+.. image:: media/expiration_dates_01.png
+    :align: center
+
+Product configuration
+---------------------
+
+Now, you have the possibility to define different dates in the
+*inventory tab* of the product form:
+
+-  Product Use Time: it’s the number of days before the goods start deteriorating, without being dangerous yet. It will be computed using the lot/serial number;
+
+-  Product Life Time: refers to the number of days before the goods may become dangerous and must not be consumed. It will be computed on the lot/serial number;
+
+-  Product Removal Time: shows the number of days before the goods should be removed from the stock. It will be computed on the lot/serial number;
+
+-  Product Alert Time: refers to the number of days before an alert should be raised on the lot/serial number.
+
+.. image:: media/expiration_dates_02.png
+    :align: center
+
+Expiration Date on Lots/Serial Numbers
+======================================
+
+When receiving a product in stock, the dates will automatically be
+updated on the corresponding lot/serial number. This update will be
+based on the reception date of the product and the times set on the
+product form.
+
+.. image:: media/expiration_dates_03.png
+    :align: center
+
+.. image:: media/expiration_dates_04.png
+    :align: center
+
+Expiration Alerts
+=================
+
+You can access all your expiration alerts from the *inventory* app. To
+do so, go to *Master Data > Lots/Serial Numbers*. There, you can use
+the pre-existing filter that shows all the lots/serial numbers that
+exceeded their alert date.
+
+.. image:: media/expiration_dates_05.png
+    :align: center