[cxx-interop] Document std::unique_ptr support

Author: egorzhdan

documentation/cxx-interop/index.md

@@ -1285,11 +1285,6 @@ The C++ caller of this function is responsible for releasing the object.
 The `SWIFT_UNSAFE_REFERENCE` annotation macro has the same effect as `SWIFT_IMMORTAL_REFERENCE`
 annotation macro. However, it communicates different semantics: the type is intended to be used unsafely, rather than living for the duration of the program.
 
-### Unique Reference Types
-
-Unique reference types, such as types passed around by `std::unique_ptr` are
-not yet supported by Swift.
-
 ## Using C++ Standard Library from Swift
 
 This section describes how to import the C++ standard library, and how

documentation/cxx-interop/status/index.md

@@ -196,10 +196,11 @@ The following C++ standard library types are supported in Swift:
 - Specializations of `std::set`, `std::multiset` and `std::unordered_set`
 - Specializations of `std::optional`
 - Specializations of `std::shared_ptr`
+- Specializations of `std::unique_ptr`
 - Specializations of `std::array`
 
-Other standard library types, like `std::unique_ptr`, `std::function` and
-`std::variant` are not yet supported in Swift.
+Other standard library types, like `std::function` and `std::variant`, are not
+yet supported in Swift.
 
 ### Other C++ Features Handled by Swift