update news

NEWS.md

@@ -1,6 +1,8 @@
 # bmm 0.4.0+
 
 ### New features
+* add a custom summary() method for bmm models
+* add a global options bmm.summary_backend to control the backend used for the summary() method (choices are "bmm" and "brms")
 * deprecate get_model_prior(), get_stancode() and get_standata(). These functions will be removed in future versions of the package. Due to [recent changes](https://github.com/paul-buerkner/brms/pull/1604) in *brms* version 2.20.14, you can now use the *brms* functions `default_prior`, `stancode` and `standata` directly with *bmm* models (alternatively, their older aliases, "get_prior", "make_stancode", "make_standata").
 
 # bmm 0.4.0