Debug install

TO DO

• Explain how to create a postgresql db in Get Started WIKI
• Explain for each env variable what is it for and how to create them
• Fix gitlab connection
• Fix magic link connection replaced by #71 (closed)
• Fix stripe webhooks

Related issues / MR

• #33 (closed)
• !6 (merged)
• !7 (merged)
• !8 (merged)
• !15 (merged)