Pin D1 not available for Oled SSD1306

[justinotherguy]

Hey there,

beautiful project - exactly what I was looking for :D
A big thank you already!

There is one thing I have come across, though:
I like to use the Wemos Boards (D1 mini), particularly because of the shields available for it.
The OLED shield uses I2C on the pins D1 + D2.
In the block "Oled SSD1306 : Initialization" I can select pins D2-D20 - but not D1.
Is there a specific reason why D1 is not in that list?

Regards, J.