move readme to restructuring root

restructuring/README.md

+This is a work-in-progress directory and part of the larger Prosa restructuring effort. As parts in Prosa are changed to comply with the “new style”, they are placed here.
+
+The behavior directory collects all definitions and basic properties of system behavior (i.e., trace-based semantics).
+
+The model directory collects all definitions and basic properties of system models (e.g., sporadic tasks, arrival curves, scheduling policies etc.)
+
+# Remarks
+
+We have chosen and applied some renaming rules for sections and definitions, cf. arrival_sequence.v and sporadic.v. Basically, we try to consistenly use `Valid*` , `*Properties` for section names about a concept `*` and `respects_*`, `valid_*` for definitions about a system model `*`.

restructuring/behavior/README.md

-The behavior directory/module collects all definitions and theories about system behavior (i.e., trace-based semantics).
-
-Any aspects related to system *modeling* (e.g., sporadic tasks, arrival curves, etc.) do *not* belong here and should go into the *model* directory/module instead. 
-
-This is a work-in-progress directory and part of the larger Prosa restructuring effort. As parts in Prosa a changed to comply with the “new style”, they are placed here. 
-
-