It's a good question, I think you should be asking that on the Adafruit forum. They need to fix the page you linked to. (+1 karma for posting the link properly.)
You might be able to figure it out by comparing to the pinout of a feather board.
If you mix up the i2c lines, it will not work, but will not do any harm, swap them if that happens. But if you mix up 3V and ground, there could be damage.
An important question is: will the chip on the display be damaged if connected to the 5V i2c pins of an Uno? If so, you will need an i2c voltage level shifter.
Thank you for your quick help. Indeed I should ask on the Adafruit forum, but I wanted to prevent another registration with user name, password, confirmation mail etc.
Just for such a simple question. Honestly I cannot believe that it need so much time.
Anyway, thank you for your words.
Best regards
Wedilo