Fix Readme
Image / links to "Integration level" and "Build Status" are broken.
If I click on the image "Install with Yunohost" I'm redirected to a page stating that the app is neither maintained officially or by the community.
This makes me wondering: Can I install this app yet? Also there are some issues/PR over https://github.com/Bridouz/gitea_ynh/issues, are they resolved here of should we re-open them to track them?