change name of chinese version index

index.cn.html

@@ -109,7 +109,7 @@
                         <div class="list-group ">
                           
                             <a href="./01.fit_a_line/index.cn.html" target="content_iframe" class="list-group-item list-group-item-action" style="border: 0px; border-bottom: 2px solid #dddfe3;">
-                                新手入门
+                                线性回归
                             </a>
                           
                             <a href="./02.recognize_digits/index.cn.html" target="content_iframe" class="list-group-item list-group-item-action" style="border: 0px; border-bottom: 2px solid #dddfe3;">
@@ -170,4 +170,4 @@
     $($(".list-group a")[0]).addClass("click_active") 
     </script>
 </body>
-</html>
\ No newline at end of file
+</html>