Update documentation

[arildm]

• [ ] In-app manual
  • [ ] Update obsolete things
  • [ ] About the 3 different modes
  • [ ] About automatic pseudonymization
  • [ ] About "Fit graph" and "show full graph"
  • [ ] About validation
  • [ ] About images link
• [ ] Update README

[arildm]

High prio in end of August