Simple Content component does not automatically show content created in the Channel Manager

The "Simple Content" component has the new "manageContent" button to create new content in the Channel Manager. However, new content created with it is not shown automatically because the "document" component parameter is not updated automatically. The resulting flow is a bit confusing: "where did the document I just created end up?".

Steps to reproduce:

1. Add a Simple Content component to a container
2. Enable the 'Content' overlay so the orange buttons are shown
3. Click the '+' button to create a new simple content document
4. Fill in all fields and click 'Continue'
5. Fill in all fields and click 'Save'

Expected: the newly created document is shown in the site

Actual: the newly created document is not visible, and the component still looks empty

The issue is caused by the fact that the hst.manageContent tag in the contentpage-main.ftl template does not specify the "parameterName" attribute:

<@hst.manageContent templateQuery="new-content-document" rootPath="content"/>

The component parameter is therefore not set to the path of the created document.