Add screenshot to step 5.6 "Close Tails Installer"

But let’s do that after #15105 (closed) is resolved.

Feature Branch: feature/15106-installation-complete

Attachments

• 

Parent Task: #14548

Related issues

• Blocked by #15105 (closed)
• Blocks #14758 (closed)

Original created by @sajolida on 15106 (Redmine)