[issue41822] Document the mean of values for sys.float_info.rounds

Change by Raymond Hettinger : -- nosy: +mark.dickinson, serhiy.storchaka, tim.peters ___ Python tracker ___ ___ Python-bugs-list mai

[issue41822] Document the mean of values for sys.float_info.rounds

New submission from Raymond Hettinger : The current docs unnecessarily refer readers to the C99 standard. "integer constant representing the rounding mode used for arithmetic operations. This reflects the value of the system FLT_ROUNDS macro at interpreter startup time. See section 5.2.4.2.2