Merge pull request #38 from relic-se/contrast-range-docs

Update `adafruit_ov5640.OV5640.contrast` value range in docstring

Author: ladyada

adafruit_ov5640/__init__.py

@@ -1509,7 +1509,7 @@ def brightness(self, value: int) -> None:
 
  @property
  def contrast(self) -> int:
- """Sensor contrast adjustment, from -4 to 4 inclusive"""
+ """Sensor contrast adjustment, from -3 to 3 inclusive"""
  contrast_abs = self._read_register(0x5587) >> 4
  contrast_neg = self._read_register(0x5588) & 8
  if contrast_neg: