[docs] Bug in https://docs.python.org/3.6/tutorial/introduction.html#strings

In the first Codeblock at the sixth example it should be:

...

...

'"Isn\'t," she said.' '"Isn't," she said.'

In the current version the answer of the interpreter shows the backslash character as well. That's not correct. Best Regards Erik Sommer -- Diese Nachricht wurde von meinem Android-Mobiltelefon mit K-9 Mail gesendet.