It should be mentioned in the documentation that 

A StopIteration exception raised in the body of a while loop will terminate (and is caught by) the while-loop, thus leading to graceful termination.

A good place would be here:
1) https://docs.python.org/3/reference/compound_stmts.html#the-while-statement

I don't know how such a StopIteration termination of a while loop
affects the else-clause. This should be clarified.

Here:
2) https://docs.python.org/3/library/exceptions.html#StopIteration
it would be good to explicitly state:

An enclosing while-loop or for-loop acts like an implicit catch for StopIteration. The StopIteration exception will terminate the loop.

(I guess, a for-loop is also just terminated when the StopIteration originates in the BODY of the loop, although this is not the typical case.)