use path.sep instead of / to accound for differnt platforms (#8380)

Signed-off-by: Emma Indal <emmai@spotify.com>

packages/techdocs-common/src/stages/generate/helpers.ts

@@ -384,7 +384,7 @@ export const createOrUpdateMetadata = async (
   // a form appropriate for invalidating the associated object from cache.
   try {
     json.files = (await getFileTreeRecursively(techdocsMetadataDir)).map(file =>
-      file.replace(`${techdocsMetadataDir}/`, ''),
+      file.replace(`${techdocsMetadataDir}${path.sep}`, ''),
     );
   } catch (err) {
     assertError(err);