Release/0.2.0

[paf31]

• [x] RFC
  • [x] Remove ComparisonTarget["path"] RFC
  • [x] Named scopes RFC
  • [x] Group by RFC
  • [x] Filter by aggregates RFC
  • [x] Nested collections RFC
• [x] Specification updates
  • [x] Changelog
  • [x] Specification pages
  • [x] Tutorial pages
  • [x] reference/types.md
• [x] Implement your feature in the reference connector
• [x] Generate test cases in ndc-test if appropriate
• [x] Does your feature add a new capability?
  • [x] Update specification/capabilities.md in the specification
  • [ ] Check the capability in ndc-test