Update docs

Author: mingxwa

docs/spec/make_proxy_view.md

@@ -5,14 +5,12 @@
 > Namespace: `pro::inline v4`  
 > Since: 3.3.0
 
-The definition of `make_proxy_view` makes use of an exposition-only class template *observer-ptr*. `observer-ptr<T>` contains a raw pointer to an object of type `T`, and provides `operator*` for access with the same qualifiers.
-
 ```cpp
 template <facade F, class T>
 proxy_view<F> make_proxy_view(T& value) noexcept;
 ```
 
-Creates a `proxy_view<F>` object containing a value `p` of type `observer-ptr<T>`, where `*p` is direct-non-list-initialized with `&value`. If [`proxiable_target<T, F>`](proxiable_target.md) is `false`, the program is ill-formed and diagnostic messages are generated.
+Equivalent to `return make_proxy_ref<observer_facade<F>>(value)`.
 
 ## Return Value
 

include/proxy/v4/proxy.h

@@ -1825,8 +1825,7 @@ constexpr proxy<F> make_proxy_ref(T& value) noexcept {
 
 template <facade F, class T>
 constexpr proxy_view<F> make_proxy_view(T& value) noexcept {
-  return proxy_view<F>{
-      details::observer_ptr<T&, const T&, T&&, const T&&>{value}};
+  return make_proxy_ref<observer_facade<F>>(value);
 }
 
 #if __STDC_HOSTED__