Add events (e.g., RHoK, Linked Open Data day) organized

[porduna]

Not just as a new item, but something that people can see in the About page.

[porduna]

This doesn't need to change the model. We added the Hackathon event type, and we can publish everything there. We only need a view showing these events.

[aitoralmeida]

Already supported in the model.