docs: Enhance documentation with detailed examples and troubleshooting tips for OSL JSON format

[SilvioGiancola]

No description provided.

[Copilot]

Pull request overview

Documentation refresh: expands the OSL JSON format guidance, getting-started walkthrough, save/load behavior, batch tools, and troubleshooting; excludes repo README files from the published site; adds changelog notes.

Changes:

• Adds examples, common-mistake tables, and notes about relative paths and grouped Q/A across multiple doc pages.
• Updates CLI script paths to tools/... and adds new converter command sections.
• Excludes top-level README.md and assets/README.md from the mkdocs build.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
mkdocs.yml	Excludes repository README files from the docs site build.
docs/OSL.md	Adds a minimal valid example and a common-mistakes table.
docs/getting_started.md	Restructures the walkthrough with tabs table and save behavior summary.
docs/saving_loading.md	Expands load/save behavior, normalization details, and persisted-fields lists.
docs/annotating.md	Clarifies per-tab workflows and the JSON fields each writes.
docs/batch_tools.md	Updates CLI script paths and adds converter command examples.
docs/troubleshooting.md	Adds JSON load, missing media, and clarified HF/video sections.
docs/changelog.md	Adds documentation notes and a release-notes link.

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