[ADD] Prose checking

[lishaduck]

There's currently no linting for markdown, etc. This is a TS config, so I'd expect this to be out of scope, but I'm documenting it in case @AndreaPontrandolfo finds some of it useful.

• npm:@eslint/markdown (currently published as npm:eslint-plugin-markdown)
  • Adds linting to JS/TS code blocks in GFM Markdown.
  • Supports ESLint 9.
  • Is an official project, uses experimental ESLint language plugin support.
• npm:eslint-plugin-mdx
  • Adds JS linting to MDX.
  • Adds JS/TS codeblock linting to MDX & GFM Markdown.
  • Supports Remark lints (including Prettier compatibility).
  • Does not officially support ESLint 9 (But works, except for GFM linting).
• npm:eslint-plugin-markdownlint
  • Runs markdownlint, converts errors to ESLint format.
• npm:@cspell/eslint-plugin
  • Spell checking for all programming languages, the ESLint plugin only checks strings, identifiers at declaration, and comments for JS/TS, preventing false positives over the CSpell CLI.