Fix minor issues

src/reference.hpp

@@ -85,7 +85,7 @@ struct ControlBlock {
  *
  * Usage:
  * - Use make_ref<T>() to create new objects
- * - Copy/assign to share ownership
+ * - Use copy() method for explicit sharing of ownership
  * - Use get(), operator*, operator-> to access the object
  * - Use operator bool() to check if valid
  * - Use reset() to release ownership
@@ -297,7 +297,8 @@ private:
  * that might be destroyed by other threads.
  *
  * Usage:
- * - Create from Ref<T> to observe without owning
+ * - Create from Ref<T> using as_weak() to observe without owning
+ * - Use copy() method for explicit copying
  * - Use lock() to attempt promotion to Ref<T>
  * - Returns empty Ref<T> if object was already destroyed
  * - Use reset() to stop observing

tests/test_reference.cpp

@@ -472,7 +472,6 @@ TEST_CASE("Polymorphic edge cases") {
     // addresses
     Interface1 *interface1_ptr = multi_ref.get();
     Interface2 *interface2_ptr = multi_ref.get();
-    MultipleInheritance *multi_ptr = multi_ref.get();
 
     // Verify that pointers are indeed different (demonstrating the issue)
     CHECK(static_cast<void *>(interface1_ptr) !=