Update docs

Author: lucic71

docs/src/codegen/types/classes.md

@@ -90,9 +90,9 @@ behind pointers, is emitted at the end of the file as an empty
 
 A constructor becomes an associated function named after the class. It opens
 with `let mut this = Self { ... }`, one field per member initializer, then runs
-the C++ body and returns `this`. Only implicit or defaulted copy and move
-constructors are supported: a user-defined one stops the translation, and the
-implicit copy is what the `Clone` impl represents.
+the C++ body and returns `this`. Copy and move constructors become `copy_from`
+and `move_from` (see [Naming](./naming.md)); the `Clone` impl calls `copy_from`
+when the copy constructor is user-defined.
 
 Methods take `&self` when `const` and `&mut self` otherwise in the unsafe model.
 In the refcount model they always take `&self`, since mutation goes through the

docs/src/codegen/types/naming.md

@@ -27,3 +27,8 @@ name unless they are overloaded, in which case the parameter types are appended
 (`method_i32`, `method_i32_const`). `operator<` is emitted as `lt`; comparison
 operators additionally produce the corresponding trait impls (`PartialOrd`,
 `Ord`, `PartialEq`).
+
+Copy and move constructors are named `copy_from` and `move_from`, and copy and
+move assignment operators `copy_assign` and `move_assign`, as long as the class
+has only one member of that kind and no method already uses the name; otherwise
+they get the overloaded form.