R.13 is out of date with C++17

[tclinken]

R.13 uses the example:

// BAD: potential leak
fun(shared_ptr<Widget>(new Widget(a, b)), shared_ptr<Widget>(new Widget(c, d)));

This could leak prior to C++17, but with the change from this accepted proposal, there is no potential leak in C++17. The explanation of this rule should be updated to reflect this.

[shaneasd]

I think this was mentioned in and is addressed by #1610