Document custom placeholders for the register interest widget and mak…

…e register interest/events widgets top level nav items.

source/docs/api/widget/index.html.md.erb

@@ -486,22 +486,34 @@ Use the `trialfire` plugin to integrate with [Trialfire](https://trialfire.com/)
 
 You can use `email-placeholder` and `name-placeholder` attributes to set custom placeholders for the name and email fields on the order form.
 
-## Events widget
+# Events widget
 
 To display a list of your upcoming and past events on your site, like what appears on your Tito public account timeline <a href="https://ti.to/events" target="_blank">here</a> for example, you can use the `<tito-events>` widget.
 
 ```html
 <tito-events account="ultimateconf"></tito-events>
 ```
 
-## Register interest widget
+# Register interest widget
+
+```html
+<tito-register-interest event="ultimateconf/2013"></tito-register-interest>
+```
 
 To add a form on your site for people to <a href="https://help.tito.io/en/articles/2003003-interested-people" target="_blank">register interest</a> in your event, you can use the `<tito-register-interest>` widget.
 
+## Custom placeholders
+
 ```html
-<tito-register-interest event="ultimateconf/2013"></tito-register-interest>
+<tito-register-interest
+  event="ultimateconf/2013"
+  email-placeholder="[email protected]"
+  name-placeholder="Michael Scott"
+  ></tito-register-interest>
 ```
 
+You can use `email-placeholder` and `name-placeholder` attributes to set custom placeholders for the name and email fields on the register interest widget.
+
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