Fix documentation of STEMMA_I2C

Co-authored-by: Dan Halbert <[email protected]>

Author: Neradoc

shared-bindings/board/__init__.c

@@ -73,8 +73,10 @@ mp_obj_t board_i2c(void) {
 MP_DEFINE_CONST_FUN_OBJ_0(board_i2c_obj, board_i2c);
 
 
-//| def SECOND_I2C() -> busio.I2C:
-//|     """Returns the `busio.I2C` object for the secondary I2C pins, usually the STEMMA[QT] connector. It is a singleton."""
+//| def STEMMA_I2C() -> busio.I2C:
+//|     """Returns the `busio.I2C` object for the STEMMA or STEMMA QT connector.
+//|     Present only if the STEMMA connector provides a second, additional I2C bus that is not the same as `board.I2C()`.
+//|     It is a singleton."""
 //|     ...
 //|