[12.0][IMP] kpi_dashboard: Add demo data and testing

kpi_dashboard/readme/CONFIGURE.rst

@@ -11,6 +11,17 @@ Configure KPIs
 #. In order to compute the KPI you can use a predefined function from a model or
    use the code to directly compute it.
 
+Using KPI with code
+~~~~~~~~~~~~~~~~~~~
+
+Define the code directly on the code field. You can use `self` and `model` as the kpi element
+The script should create a variable called `result` as a dictionary that
+will be stored as the value.
+For example, we can use::
+
+    result = {}
+    result['value'] = len(model.search([('id', '=', %s)]))
+    result['previous'] = len(model.search([('id', '!=', %s)]))
 
 Configure dashboards
 ~~~~~~~~~~~~~~~~~~~~