[ADD] purchase: How to check that everything is working fine?

https://docs.google.com/document/d/1wSuLN2vQvcp0PXP6mzEEXxfnjMb9N5ErYSRO9eOB_uY/edit?usp=sharing

purchase/replenishment/trouble_shooting/is_everything_ok.rst

@@ -2,4 +2,43 @@
 How to check that everything is working fine?
 =============================================
 
-*Coming soon...*
+Vendor Bills
+============
+
+Even if you don't have the rights to the accounting application, you can
+still control the vendor bills.
+
+Go to the **Purchases** application: :menuselection:`Control --> Vendor Bills`.
+
+.. image:: media/is_everything_ok01.png
+    :align: center
+
+Incoming Products
+=================
+
+Even if you don't have the rights to the inventory application, you can
+still control the incoming products.
+
+Go to the **Purchases** application: :menuselection:`Control --> Incoming Products`.
+
+.. image:: media/is_everything_ok02.png
+    :align: center
+
+Procurements exceptions
+=======================
+
+Here, you need the **Inventory Manager** access rights.
+
+Go to the **Inventory** application: :menuselection:`Control --> Procurement Exceptions`.
+
+.. image:: media/is_everything_ok03.png
+    :align: center
+
+To understand why the procurement is not running, open the exception and
+check the message in the chatter.
+
+.. image:: media/is_everything_ok04.png
+    :align: center
+
+Usually, the problem is located on the procurement rules. Either there
+are no stock rules, or there are no vendor associated to a product.