next.js/apps/docs/source.config.ts

import {
  defineConfig,
  defineDocs,
  frontmatterSchema,
  metaSchema,
} from 'fumadocs-mdx/config'

// You can customise Zod schemas for frontmatter and `meta.json` here
// see https://fumadocs.vercel.app/docs/mdx/collections#define-docs
export const docs = defineDocs({
  docs: {
    schema: frontmatterSchema,
  },
  meta: {
    schema: metaSchema,
  },
  dir: '../../docs',
})

export default defineConfig({
  mdxOptions: {},
})