Support dynamic default time from another field

web_datetime_picker_default_time/readme/USAGE.md

@@ -1,5 +1,21 @@
-You can define the default time as follows :
+You can define the default time as follows for a static value:
 
-.. code-block:: xml
+```xml
+    <field name="your_datetime_field" options="{'defaultTime': {'hour': 8, 'minute': 30, 'second': 15 }}"/>
+```
 
-   <field name="your_datetime_field" options="{'datepicker': {'defaultTime': {'hour': , 'minute': 30, 'second': 15 }}}"/>
+Otherwise you can also use a JSON field to make it dynamic through a compute function,
+and reference this field in the view:
+
+```python
+   start_time = field.Json(compute="_compute_start_time")
+
+   def _compute_start_time(self):
+       for rec in self:
+           rec.start_time = {'hour': 8, 'minute': 30, 'second': 15 }
+```
+
+```xml
+   <field name="start_time" invisible="1" />
+   <field name="your_datetime_field" options="{'defaultTime': 'start_time'}"/>
+```