docs: support generating sidebar items with tags (#10672)

* docs: support generating sidebar items with tags

* small fix

* fix dependencies

* test

* test fix

* test fix

* test fix

* test fix

* another fix

* revert change

* fix for resources

www/packages/docs-utils/src/get-file-slug-sync.ts

@@ -0,0 +1,11 @@
+import { matter } from "vfile-matter"
+import { readSync } from "to-vfile"
+import { FrontMatter } from "types"
+
+export function getFileSlugSync(filePath: string): string | undefined {
+  const content = readSync(filePath)
+
+  matter(content)
+
+  return ((content.data.matter as FrontMatter).slug as string) || undefined
+}