[Sonica-B]

Description

docs/source/content/tutorials.md indexed 12 notebooks. demos/ has 38, and 19 of them were not linked or named on any page under docs/source/content/ (checked on dev at 34c5d77). New users land on this page, so those demos were effectively hidden, including the Inspect and vLLM driver, multimodal (Gemma 3, LLaVA), DLA, direct path patching and Patchscopes notebooks.

This PR:

• adds one bullet for each of the 16 unlinked user-facing notebooks. Each description comes from the notebook's intro cell or, where it has none (T5), from its section headings;
• groups the list under five headings: Getting started, Interpretability techniques, Models and architectures, Backends and integrations, Training and research. Existing bullets keep their wording;
• rewrites the LLaMA entry. Its "7B parameter version for now until multi-GPU support is added" note no longer matches the notebook, which now loads meta-llama/Llama-3.2-1B or locally converted LLaMA weights;
• adds a one-line pointer to the notebooks other pages already link: Backward Lens, Jacobian Lens and SVD Circuits (analysis_tools.md, jacobian_lens_fitting.md) and the new SwiGLU Gate-Sign demo (hook_system.md).

No notebook content changed.

Left out on purpose:

• ARENA_Content.ipynb: code-only ARENA course snippets that run under notebook-checks. It has no prose.
• Colab_Compatibility.ipynb: the legacy compatibility ledger, which is a test by its own description.
• Santa_Coder.ipynb: it has no markdown cells, and despite the name it loads bigscience/bloom-560m and checks parity against HF. I didn't want to list it under a misleading title. I'm happy to add it as a BLOOM entry, or to leave a rename for a separate PR.

Links use blob/main/... like the existing bullets. All 16 new notebooks already exist on main. I'm happy to regroup or trim if you prefer a flat list.

No linked issue: this is a docs gap I found while reading the 4.x demos.

Type of change

• This change requires a documentation update

Screenshots

Checklist:

• I have made corresponding changes to the documentation
• My changes generate no new warnings (local build-docs on 34c5d77: 588 warnings before and after, identical sets, none from tutorials.md)
• New and existing unit tests pass locally with my changes (not run: docs-only change, no code touched)
• I have not rewritten tests relating to key interfaces which would affect backward compatibility

[jlarson4]

Thank you for catching and fixing this @Sonica-B. Just one note on the two different "Start" sections that are back-to-back on the tutorials.md page now.

[jlarson4]

The existing "Where To Start" section above sends new users to the Main Demo and the exploratory analysis notebook through different routes, so the page now has two "start here" sections. Can we restructure these to either be a single section or rename this section to "Primary Demos", "Core Demos", or the like?