update bookdowm doc
diff --git a/docs/bookdown/index.html b/docs/bookdown/index.html
index 4e6f8cf..036a660 100644
--- a/docs/bookdown/index.html
+++ b/docs/bookdown/index.html
@@ -25,7 +25,7 @@
<meta name="author" content="Hao Zhu">
-<meta name="date" content="2018-10-03">
+<meta name="date" content="2018-10-08">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="apple-mobile-web-app-capable" content="yes">
@@ -158,7 +158,7 @@
<div id="header">
<h1 class="title">Using kableExtra in Bookdown</h1>
<p class="author"><em>Hao Zhu</em></p>
-<p class="date"><em>2018-10-03</em></p>
+<p class="date"><em>2018-10-08</em></p>
</div>
<div id="introduction" class="section level1">
<h1><span class="header-section-number">Chapter 1</span> Introduction</h1>