docs: fix broken tutorial links and remove redundant file

[ykdojo]

Changes Made

Fixed broken documentation links that were preventing users from navigating to examples from the quickstart guide:

• Updated quickstart.md to link to /examples/ instead of the old /resources/tutorials/ path
• Fixed broken reference in custom-code/udfs.md to point to the new examples location
• Removed redundant docs/resources/tutorials.md file since a redirect is already configured in mkdocs.yml

Checklist

• Documentation builds and is formatted properly

Internal

Closes https://linear.app/eventual/issue/EVE-858/broken-links-on-quickstart

[greptile-apps]

Greptile Summary

This PR fixes broken documentation navigation by updating tutorial links to use the new examples structure. The changes address a documentation reorganization where content was moved from /resources/tutorials/ to /examples/.

Specifically, the PR:

• Updates the quickstart guide to link to the new examples directory structure (../examples/mnist/, ../examples/llms-red-pajamas/, etc.) instead of the old tutorial paths
• Fixes a broken reference in the UDF documentation that points to the document processing example
• Removes the redundant docs/resources/tutorials.md file, which was no longer needed since a redirect already exists in mkdocs.yml that maps resources/tutorials.md to examples/index.md

This change aligns with the existing redirect configuration and ensures users can successfully navigate from documentation to working examples. The restructuring improves documentation maintenance by eliminating duplicate content and establishing a single source of truth for example listings in the examples directory.

Confidence score: 5/5

• This PR is safe to merge with minimal risk as it only fixes broken documentation links
• Score reflects straightforward documentation updates with no code logic changes
• No files require special attention as all changes are simple link updates and file cleanup

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[desmondcheongzx]

Would also like to replace these tutorials with our newer, more representative tutorials. i.e. document processing, audio transcription, embeddings.