Layout of the readme is not always good

[AlexanderFabisch]

Describe the bug Layout in readme is not always good.

To Reproduce Steps to reproduce the behavior:

1. Go to main GitHub page of phobos
2. Scroll down to readme
3. Change size of the browser window

Expected behavior There should be a line break before the image

Screenshots

Desktop (please complete the following information):

• OS: Ubuntu
• Browser: firefox