Document that an end-time attribute needs to be specified for the temporal dimension

Author: manisandro

src/topics/TimeManager.md

@@ -8,5 +8,8 @@ To view and manage temporal layers in QWC, add a new time dimension, selecting a
 
 For the time markers functionality in the Time Manager plugin to work correctly, you also need to [enable](../configuration/ServiceConfiguration.md#enabling-services) the [`qwc-feature-info-service`](https://github.com/qwc-services/qwc-feature-info-service).
 
-*Note:* The QGIS Layer Properties → Temporal settings are ignored by QGIS Server and hence have no effect in QWC.
+*Note:*
+
+- An end-time attribute must be specified, or else the QGIS Server won't render any feature even if the passed time dimension is greater than the start-time attribute. If your data does not have an end attribute, you can for instance create a view which adds an end attribute with value i.e. `now()` or a value far in the future.
+- The QGIS Layer Properties → Temporal settings are ignored by QGIS Server and hence have no effect in QWC.