Add an OTel training+certs showcase

[chalin]

OTel training+certs will be available in the next couple of months. We'll need to add a section or page to showcase them.

@caniszczyk:

Something like https://prometheus.io/support-training/

Maybe also rework vendors? (Cf. #2178)

Reference:

• Add training+certs showcase to OTel website cncf/techdocs#197

[zzadxz]

Hey! Can I take this one?

[svrnm]

Hey @zzadxz,

since we are still waiting for the trainings+certs being available within the next couple of months, this is not something you can help with right now. Take a look at the issues we have marked with "help wanted" or "good first issue" to find some where you can start immediately