Fix wrong statement in code sample in std::is_trivally_copyable_v

[YukunJ]

Brief: wrong statement in the code sample in std::is_trivally_copyable_v section.

// T 不是 trivial（用户定义了构造），通常也不是 trivially_copyable

This is not a true statement.

I was originally inspired by

可以安全地用 memcpy 按字节拷贝（拷完目标有同样的对象表示，且能正常析构）

and thought T would be trivially_copyable and confused by seeing the tutorial stating 通常也不是 trivially_copyable.

And I ran the local experiment and looked up standard docs for more clarification on this.

• https://en.cppreference.com/cpp/types/is_trivially_copyable
• https://eel.is/c++draft/class.prop?#11

QA:
See godbolt sample: https://godbolt.org/z/dT9c8dWWj

@Charliechen114514

[Charliechen114514]

收到，这里的确是一处笔误，感谢您的批评指正！