Update presentations and talks link in community page

[candita]

What would you like to be added:

The last update to https://gateway-api.sigs.k8s.io/contributing/#presentations-and-talks was 5 years ago and needs to be updated with KubeCon talks and presentations.

Why this is needed:

We've had some great talks since then, and they should be added to help promote the project. It would be nice to update this after every KubeCon, but at least once a year would suffice.

[kundan2707]

/assign

[kundan2707]

I will find out all sessions and update this page

[shaneutt]

Thanks @candita and @kundan2707.

/triage accepted

(note: you'll be able to find some of them here: kubernetes/community#8356)