Improve seeds

[joaodiaslobo]

Check for existing issues

• Completed

Describe the feature

Current seeds don't represent real application use all that well.
Main areas of focus should be:

• Organizations: should have logos (maybe use something like GitHub avatars?
• Activities: should have images, a human written like description, enrollments.
• Announcements: should have human written like text, images.

If applicable, add mockups / screenshots to help present your vision of the feature

No response