fix(build): `createContentLoader` generates invalid url when `srcDir` is set (#2578)

BREAKING CHANGE: `createContentLoader` will now resolve globs relative to `srcDir` instead of `root`

docs/guide/data-loading.md

@@ -91,7 +91,7 @@ import { createContentLoader } from 'vitepress'
 export default createContentLoader('posts/*.md', /* options */)
 ```
 
-The helper takes a glob pattern relative to [project root](./routing#project-root), and returns a `{ watch, load }` data loader object that can be used as the default export in a data loader file. It also implements caching based on file modified timestamps to improve dev performance.
+The helper takes a glob pattern relative to the [source directory](./routing#source-directory), and returns a `{ watch, load }` data loader object that can be used as the default export in a data loader file. It also implements caching based on file modified timestamps to improve dev performance.
 
 Note the loader only works with Markdown files - matched non-Markdown files will be skipped.
 

src/node/contentLoader.ts

@@ -115,7 +115,7 @@ export function createContentLoader<T = ContentData[]>(
           })
           const url =
             '/' +
-            normalizePath(path.relative(config.root, file)).replace(
+            normalizePath(path.relative(config.srcDir, file)).replace(
               /\.md$/,
               config.cleanUrls ? '' : '.html'
             )