[BUG] Images and icons are not displayed in GH organization profile

[tbouffard]

Describe the bug

Additional context
This happens for both html syntax or markdown image tag

The cheat sheet image only uses markdown syntax ![Cheat sheet image](cheat_sheet.png), but the resulting url used in the generated overview page is https://github.com/process-analytics/.github/blob/main/cheat_sheet.png. Everything acts as if the README file was at the root of the repository whereas it is located in the profile subfolder
The Hacktoberfest image correctly displays: the image is not hosted in the repository, we use an url targetting a dedicated commit of the bpmn-visualization-examples repository.

Element using the html syntax

• header image: https://github.com/process-analytics/.github/blob/main/header.svg
• same for logos

[tbouffard]

Quick fix implemented with #7