The easiest way to make text editable in Taxi is to wrap the <editable> tag around a piece of text.
<editable name="" label="">text</editable>
However sometimes you may need to break this tag apart, whilst maintaining content that has already been added in Taxi using the Design System. You can do this by using a text field, with the name="content".
<editable name="" label="">
<field type="text" name="content" label="Text"></field>
<content replace="{{content}}"></content>
</editable>