Reference material from BiDS

[Schpidi]

The material is available at https://eo4society.esa.int/resources/esas-2025-big-data-foundations-for-earth-observation-training-course/

This issue is to discuss which and how to reference this material on the EarthCODE Portal.

Moved from https://github.com/ESA-EarthCODE/PM-Tasks/issues/61

[Schpidi]

Need to add a dedicated space for educational material.