Update STYLEGUIDE.md

STYLEGUIDE.md

@@ -2,6 +2,7 @@ This is a collection of style guides for Kibana projects. The include guides for
 
 - [JavaScript](#javascript-style-guide)
 - [Kibana Project](#kibana-style-guide)
+- [Html](#html-style-guide)
 
 # JavaScript Style Guide
 
@@ -855,6 +856,24 @@ require('ui/routes')
 });
 ```
 
+# Html Style Guide
+
+### Multiple attribute values
+
+When a node has multiple attributes that would cause it to exceed the line character limit, each attribute including the first should be on its own line with a single indent. Also, when a node that is styled in this way has child nodes, there should be a blank line between the openening parent tag and the first child tag.
+
+```
+<ul
+  attribute1="value1"
+  attribute2="value2"
+  attribute3="value3">
+  
+  <li></li>
+  <li></li>
+  ...
+</ul>
+```
+
 # Attribution
 
 This JavaScript guide forked from the [node style guide](https://github.com/felixge/node-style-guide) created by [Felix Geisendörfer](http://felixge.de/) and is