docs: add Symfony-specific page

[dunglas]

Docs for the Symfony integration, as for Laravel and WordPress.

[Copilot]

Pull request overview

Adds a dedicated Symfony integration documentation page and updates existing docs to reference it, aligning Symfony with the existing Laravel/WordPress integration docs.

Changes:

• Add new docs/symfony.md covering Docker, local setup, worker mode, hot reload, asset precompression, and embedding.
• Update docs/worker.md to point Symfony readers to the new Symfony page.
• Link the Symfony integration docs from README.md and tidy some Markdown formatting in README.md and CONTRIBUTING.md.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 1 comment.

File	Description
docs/worker.md	Replaces the Symfony Runtime subsection with a pointer to the new Symfony documentation.
docs/symfony.md	New Symfony integration page (setup, worker mode, hot reload, assets, embedding).
README.md	Adds Symfony integration link in Docs and updates the Symfony entry in Examples/Skeletons; minor whitespace cleanup.
CONTRIBUTING.md	Markdown formatting cleanup for nested code blocks and escaping * in file globs.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.