docs: add link to langfuse in LangfuseConnector

[marcklingen]

Related Issues

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Proposed Changes:

I propose to add a link to Langfuse to help people figure out what Langfuse actually is when browsing the api reference.

How did you test it?

I did not test it

Notes for the reviewer

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Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.

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[marcklingen]

@vblagoje What do you think? I saw a link when checking out the chroma integration api reference and thought it would be useful on the langfuse page as well.

[vblagoje]

Sounds good @marcklingen ! A small ask from our side is to add "Usage Notice" from https://docs.haystack.deepset.ai/docs/langfuseconnector somewhere in your https://langfuse.com/docs/integrations/haystack/get-started page as well. We had some users accidentally import one of the Haystack components before setting tracing enabled, leading to improper initialization ultimately resulting in no logs showing up in Langfuse. It's a common mistake our users face, see:

• OpenAIChatGenerator does not trace results haystack#8126
• Langfuse Connector Failing to Trace Pipeline Data #789

[marcklingen]

Thank you!

Got this feedback as well and added a note here: https://langfuse.com/docs/integrations/haystack/get-started#set-environment-variables

[vblagoje]

Thanks for this update @marcklingen