add DAX benchmark for Nov 17

20211117/20211117_DAX_benchmark.csv

+"forecast_date","target","horizon","q0.025","q0.25","q0.5","q0.75","q0.975"
+"2021-11-17","DAX","1 day",-2.65844263691718,-0.478408853013734,0.0754703798988565,0.65948147757644,2.22946787319034
+"2021-11-17","DAX","2 day",-3.76658704113496,-0.730638752085122,0.165072327412297,0.907244580165889,3.10108794007109
+"2021-11-17","DAX","5 day",-4.73040567059547,-0.805625742830962,0.168228145854687,1.1996376118808,3.89032640718187
+"2021-11-17","DAX","6 day",-5.23203014061953,-0.928194576204255,0.246671919221697,1.39631925115538,4.57407374600166
+"2021-11-17","DAX","7 day",-5.68685922947709,-1.06110544198859,0.380815682407221,1.49206818774594,5.19223708311003