update README for new datetime handling rules; closes #81 and #79, rule becomes 'if you want timezone information, use DateTimeOffset' ; DateTime now explicitly works in UTC, handling of DateTimeKind.Unspecified controlled by UnspecifiedDateTimeKindBehavior
update README for new datetime handling rules; closes #81 and #79, rule becomes 'if you want timezone information, use DateTimeOffset' ; DateTime now explicitly works in UTC, handling of DateTimeKind.Unspecified controlled by UnspecifiedDateTimeKindBehavior

NickCraver/Jil,m0sa/Jil,buybackoff/Jil,mgravell/Jil,kevin-montrose/Jil,larrynung/Jil