fix: sitemap generation with SDKs disabled (#38528)

Sitemap generation is failing when SDKs are disabled because it expects
to find generated files for the disabled SDKs. Fix by filtering to only
generate sitemap entries for enabled SDKs.

Co-authored-by: Chris Chinchilla <chris.ward@supabase.io>

apps/docs/internals/files/reference-lib.ts

@@ -5,6 +5,7 @@ export async function generateReferencePages() {
   return (
     await Promise.all(
       Object.keys(REFERENCES)
+        .filter((key) => REFERENCES[key].enabled !== false)
         .flatMap((key) => {
           if (REFERENCES[key].versions.length === 0) {
             return [