docs: add galileo observability example

[Anaisdg]

This PR adds Galileo, an AI evaluation and observability platform, to the docs.

Thank you!

[koverholt]

Thanks for this PR and for your contribution! ❤️

I left a few formatting fixes as suggestions. Other than those, a big issue is that I tried the code example in this PR and I'm not seeing traces appear in Galileo.

It looks like the sample code in this PR uses GalileoSpanProcessor(), but the linked example in your sdk-examples repo uses a different approach with OTLPSpanExporter() + BatchSpanProcessor() and manually sets the endpoint and headers.

Could you update the sample code in this PR to match the working GitHub example, or a simplified version of it? Then we can re-test when ready. Thanks!

[Anaisdg]

@koverholt Thank you so much for your review! I really appreciate it.
Yes that is the new method that handles the headers automatically. Yes I've submitted a PR for the linked example. I'm working on getting the review there/for it to be merged. I'll update here when it has been merged. I apologize for jumping the gun there.

[koverholt]

Got it! Thanks for letting us know, now I see the open PR and understand the dependency & status.

I'll label this as blocked for now while rungalileo/sdk-examples#144 is in progress. And let us know when we can re-test. Thanks!