added instruction on import

import.py

+#To import data you need a excel style CSV (";" as seperator) with the first as short url (e.g. kurz.ml/example) and in the seccond row the long url (e.g http://example.com).
+#Then run docker -it <container_name> python3 import.py Now you can paste the CSV as text and press enter again at the end
 import sqlite3
 import os
 def table_check(): #Check if database exists