Feedback on /solution/machine-learning: Add information about integration with Open WebUI

[amotl]

Documentation feedback

• Page title: Machine learning
• Page URL: https://cratedb.com/docs/guide/solution/machine-learning/index.html
• Source: https://github.com/crate/cratedb-guide/blob/main/docs/solution/machine-learning/index.md

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While ClickHouse acquired LibreChat, we could at least present something with Open WebUI, deliberatly selected at that time because LibreChat's Code Interpreter API wasn't open.

• Open WebUI: Add full end-to-end example rig cratedb-examples#1038