In this place you can link the second text you write and share in google-docs. 

Go to "Externe Inhalte" and look for this icon:

Drag it in you page and insert the html code from your document in google-docs.

Do you know how to get the code in google docs?

It´s easy.

1. Just open your document in google-docs

2. Under "Datei/Archiv" choose the option "im Web veröffentlichen/publish on web"

3. Google will ask you if you´re sure about it. Say yes.

4. Copy the code "iframe src". It´s the last one and the biggest one.

5. This is the code you should paste in Mahara

Once linked in, you can keep working on this text im Google and the text will be actualized each five minutes in Mahara.