move to a seperate docs directory

docs/SPEC.md

@@ -0,0 +1,35 @@
+# SPEC - [project name]
+
+This file defines WHAT the project does. 
+
+## Goal
+
+One or two sentences about what this project will solve and for who. 
+
+## Acceptance criteria
+
+Project is ready when following concrete criteria are met and tested:
+
+- [ ] [criteria 1]
+- [ ] [criteria 2]
+
+## Constraints
+
+Technical boundaries and limitations:
+
+- Constraint 1
+- Constraint 2
+
+## Out of scope
+
+What is not part of this project:
+
+- Out of scope 1
+- Out of scope 2
+
+## Invariants
+
+Things that must never be broken:
+
+- Invariant 1
+- Invariant 2