editable content in react or handlebars component

You can add properties to a component to allow simple configuration. 

For example, the following component json:

{
  "id" : "Announcement",
  "markupLanguage" : "HANDLEBARS",
  "defaults" : {
    "config" : {
      "applicablePages" : [ ],
      "description" : "",
      "fetchedContent" : null
    },
    "props" : [ {
      "id" : "announcement_text",
      "dataType" : "STRING",
      "list" : false,
      "label" : "Announcement Text",
      "description" : "Announcement text to display",
      "control" : "INPUT"
    } ]
  },
  "components" : [ {
    "id" : "custom.widget.Announcement"
  } ],
  "grouping" : "CUSTOM",
  "scriptGroups" : null,
  "aboutThis" : null
}

Adds a simple input box to the component settings in designer where an Admin can add announcement text.

I handlebars, I access the text with {{component.props.announcement_text}}