This could be added to the bottom of the schematics page in the wiki:
=== Unlabeled variable address i2c module===
//this is for a unlabeled i2c LCD interface board which allows for changing its address
// addr, en,rw,rs,d4,d5,d6,d7
LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7); // Set the LCD I2C address
// The address pins A0-A2 are pulled high with the three 10k resistors at the bottom of the picture. If the three pads A0-A2 are jumpered, the address is changed to 0x20.