docs: fix Ollama engine name from ollama_engine to ollama

[singhvishalkr]

Summary

• The Ollama integration docs reference ollama_engine as the ML engine name, but the handler registers itself as ollama.
• Users following the docs verbatim get an engine mismatch error.

Changes

• docs/integrations/ai-engines/ollama.mdx: Replace all 5 occurrences of ollama_engine with ollama so the examples work out of the box.

Fixes #12011

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[singhvishalkr]

I have read the CLA Document and I hereby sign the CLA

[singhvishalkr]

This fixes #12011 — the Ollama docs reference ollama_engine as the engine name, but the handler actually registers as ollama. Users following the docs verbatim would get an engine mismatch. All 5 occurrences in the file are updated consistently.

[ZoranPandovski]

Thanks

[singhvishalkr]

Thanks for the review, @ZoranPandovski! If #12361 (the CREATE MODEL/PREDICTOR typo fix) is also worth a quick look, it's a similar 2-line docs correction.