升级依赖，增加分类试题

Author: diguage

docs/0000-23-monotonic-stack.adoc

@@ -45,9 +45,14 @@ for (int i = 1; i < nums.length; i++) {
 . xref:0084-largest-rectangle-in-histogram.adoc[84. Largest Rectangle in Histogram]
 . xref:0155-min-stack.adoc[155. Min Stack] -- 这个辅助栈也可以认为是一种单调栈。
 . xref:0239-sliding-window-maximum.adoc[239. Sliding Window Maximum]
+. xref:0316-remove-duplicate-letters.adoc[316. Remove Duplicate Letters]
+. xref:0402-remove-k-digits.adoc[402. Remove K Digits]
 . xref:0496-next-greater-element-i.adoc[496. Next Greater Element I]
 . xref:0503-next-greater-element-ii.adoc[503. Next Greater Element II]
+. xref:0581-shortest-unsorted-continuous-subarray.adoc[581. Shortest Unsorted Continuous Subarray]
 . xref:0654-maximum-binary-tree.adoc[654. Maximum Binary Tree]
+. xref:0739-daily-temperatures.adoc[739. Daily Temperatures]
+. xref:0901-online-stock-span.adoc[901. Online Stock Span]
 
 
 == 参考资料

pom.xml

@@ -23,8 +23,8 @@
     <maven-javadoc-plugin.version>3.8.0</maven-javadoc-plugin.version>
     <fizzed-watcher-maven-plugin.version>3.7.0</fizzed-watcher-maven-plugin.version>
 
-    <asciidoctorj.version>3.0.0-alpha.2</asciidoctorj.version>
-    <asciidoctorj-pdf.version>2.3.17</asciidoctorj-pdf.version>
+    <asciidoctorj.version>3.0.0-beta.1</asciidoctorj.version>
+    <asciidoctorj-pdf.version>2.3.18</asciidoctorj-pdf.version>
     <asciidoctorj-epub3.version>2.1.3</asciidoctorj-epub3.version>
     <asciidoctorj-diagram.version>2.3.1</asciidoctorj-diagram.version>
     <asciidoctor-multipage.version>0.0.19</asciidoctor-multipage.version>