feat: add lastbib package hint

aust-book-report-example.tex

@@ -1,5 +1,5 @@
 \documentclass{aust-thesis}
-\usepackage{amsmath}
+\input{aust-thesis-example/packages.tex}
 
 \austbookreportsetup{
   level       = {硕士研究生读书报告},
@@ -10,6 +10,7 @@
   mentor      = {张三},
   direction   = {无机物烹饪},
   title       = {意大利面与45号混凝土的微观级复合拌合研究},
+  % You can use "lastbib" provided \LastBib macro to dynamic apply for this field
   refcnt      = {12},
   school      = {打灰学院},
   date        = {2026年04月01日}