[docs] floor division, python intro

Learning python, "Informal Intro" 3.1.1, Numbers. The text says "do floor division <https://docs.python.org/3/glossary.html#term-floor-division> and get an integer result (discarding any fractional result)" I've tested and it appears that floor division rounds down to the nearest integer. (Above is not true for negative values with fractional parts. 3.333 rounds to 3, -3.333 rounds to -4.) -- Martin Rinehart Frontend Engineering <http://martinrinehart.com> (845) 610-5597