add Loading doc

doc/themes/next/source/css/_custom/custom.styl

@@ -1,4 +1,16 @@
 // Custom styles.
+
+.container:before{
+  content: "";
+  opacity: 0.1;
+  top: 0;
+  left: 0;
+  bottom: 0;
+  right: 0;
+  position: absolute;
+  z-index: -1; 
+  background: url(https://raw.githubusercontent.com/HandyOrg/HandyOrgResource/master/HandyControl/Resources/cloud.png);
+}
 .posts-expand .post-body img {
   margin: 3px;
   display: inline;