rewrite the roadmap

docs/src/dev_roadmap.md

@@ -5,19 +5,12 @@ CurrentModule = Copulas
 # Development roadmap
 
 We hope to implement a few more copula models into this package. The next ones to be implemented will probably be: 
-- Extreme values copulas. 
+- Liouville
 - Nested Archimedeans (for any generators, with automatic nesting conditions checks). 
 - Bernstein copula and more general Beta copula as smoothing of the Empirical copula. 
 - `CheckerboardCopula` (and more generally `PatchworkCopula`)
-
-More precisely, the following directions could be pursued:
-
-**Next:**
-- More documentation and tests for the current implementation. 
-- Docs: show how to use the `WilliamsonCopula` to implement generic Archimedeans.
 - Give the user the choice of fitting method via `fit(dist,data; method="MLE")` or `fit(dist,data; method="itau")` or `fit(dist,data; method="irho")`.
 - Fitting a generic archimedean with an empirically produced generator
-- Automatic checks of generator d-monotony ? Dunno if it is even possible. 
 
 **Maybe later:**
 - `NestedArchimedean`, with automatic checking of nesting conditions for generators.