Add information about || and && to grammar describing `while let`.#772

Merged

Centril merged 2 commits intorust-lang:masterfrom steffahn:master

Apr 8, 2020

+7-3

Commits on Mar 4, 2020

Add information about || and && to Grammar describing while let.
steffahn
committed
Remove duplicated explanation about lazy boolean operators in while let,
steffahn
committed