fixup! diigo-cache: RSS in diigo's export shape, from cached items

compare-export.ts: the manual drops "exits 2 on bad usage"; it's the
convention, and BAD_USAGE documents it.

Generated-by: Claude Opus 5.5

diigo-cache/scripts/compare-export.ts

@@ -7,8 +7,7 @@
  * Generates RSS from the cache's items (src/rss.ts) and compares it with
  * the export, keyed on link: title, tags, description, highlights and
  * sticky notes. Prints counts to stdout; writes <out-dir>/from-cache.rss
- * and <out-dir>/report.json (mismatched links, by category). Exits 2 on
- * bad usage.
+ * and <out-dir>/report.json (mismatched links, by category).
  */
 import * as nodeFs from "node:fs/promises";
 import { basename, join } from "node:path";