submodule: update handbook - add handbook asset spec link

Guo-Zhang · Guo-Zhang · commit c259a2059a9a · 2026-04-08T20:51:11.000+08:00
diff --git a/docs/handbook b/docs/handbook
@@ -1 +1 @@
-Subproject commit 250377ecb24ee02b281fce518969556302c503b1
+Subproject commit f598e93397278f0b729309f4e91ef6566fe1ea6b
