[DOCS] Behavior of left join using is not covered by docs

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/9.6/static/sql-select.html
Description:

At the time, the documentation (here:
https://www.postgresql.org/docs/9.6/static/sql-select.html) on using keyword
says:

Also, USING implies that only one of each pair of equivalent columns will be
included in the join output, not both.

It's not clear which column will be chosen in case of LEFT/RIGHT JOIN. At
the time, my tests show that left column will be chosen in case of left join
and right column will be chosen in case of right (looks logical).

Is my understanding correct? Is it possible to cover this behavior by
documentation?