docs[minor]ci[minor]: Add script & CI to check recurring links daily (#19100)

docs/scripts/check-broken-links.js

@@ -0,0 +1,7 @@
+// Sorry py folks, gotta be js for this one
+const { checkBrokenLinks } = require("@langchain/scripts/check_broken_links");
+
+checkBrokenLinks("docs", {
+  timeout: 10000,
+  whitelist: ["microsoft.com"],
+});