The VIL parameter is limited by the IC SN74LVC1T45 which is a bus transceiver where the external IO pins (pin 0 included) are connected to. Its datasheet is available here: SN74LVC1T45 Single-Bit Dual-Supply Bus Transceiver With Configurable Voltage Translation and 3-State Outputs.
From the Arduino Expansion Board perspective, the VIL value depends on the IOREF selection. The IOREF can be set to 3.3V or 5V. Check the table below to know the VIL value according to the IOREF selection:
IOREF (V) VIL (V) 5 1.5 3.3 0.8
The table above applies for pins 0 to 13. The default value of IOREF is 5V. This selection is made through the jumper J9 as you can check in Intel® Edison Boards — Jumper Headers.