docs: add linting and code snippet validation

[sarahxsanders]

Description

This PR introduces linting and code snippet validation for GraphQL snippets. JS snippets are commented out on this PR, because I will modernize the JS code snippets first.

Changes

• Updated ESLint config to lint Markdown and MDX files in the repository + special handling for documentation snippets.
• Created a validate-snippets.js script that extracts code snippets from MDX files and validates them against parsers. Note, I temporarily commented out JS validation logic until those code snippets are modernized to meet the latest standards.
• Set up docs validation workflow for GHA to run on PRs. This checks for broken links and code snippets.
• Fix: Added <!-- snippet-ignore --> for GQL snippets causing errors

Comments

• If this looks good, I will expand the same logic/implementation to https://github.com/graphql/graphql-js

Review

• @benjie

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Name	Status	Preview	Comments	Updated (UTC)
graphql-github-io	❌ Failed (Inspect)			Apr 8, 2025 8:15am