removed export of to_sampleable since it currently has no purpose +

fixed docs for `returned`

Author: torfjelde

docs/src/api.md

@@ -112,7 +112,7 @@ One can include models and call another model inside the model function with `le
 to_submodel
 ```
 
-Note that a `[returned(::DynamicPPL.Model)](@ref)` is only sampleable; one cannot compute `logpdf` for its realizations.
+Note that a `[to_submodel](@ref)` is only sampleable; one cannot compute `logpdf` for its realizations.
 
 In the past, one would instead embed sub-models using [`@submodel`](@ref), which has been deprecated since the introduction of [`to_submodel(model)`](@ref)
 
@@ -126,6 +126,11 @@ In the context of including models within models, it's also useful to prefix the
 prefix
 ```
 
+Under the hood, [`to_submodel`](@ref) makes use of the following method to indicate that the model it's wrapping is a model over its return-values rather than something else
+
+```@docs
+returned(::Model)
+```
 
 ## Utilities
 

src/DynamicPPL.jl

@@ -123,7 +123,6 @@ export AbstractVarInfo,
     unfix,
     prefix,
     returned,
-    to_sampleable,
     to_submodel,
     # Convenience macros
     @addlogprob!,

src/model.jl

@@ -1274,6 +1274,7 @@ end
 
 is_rhs_model(x::Sampleable) = true
 
+# TODO: Export this if it end up having a purpose beyond `to_submodel`.
 """
     to_sampleable(model)
 
@@ -1315,10 +1316,11 @@ function rand_like!!(
     return _evaluate!!(model_wrap.model, varinfo, context)
 end
 
+
 """
-    returned(model::Model)
+    returned(model)
 
-Return a `model` wrapper indicating that this a model over the return-values.
+Return a `model` wrapper indicating that it is a model over its return-values.
 """
 returned(model::Model) = ReturnedModelWrapper(model)