Document Clock Divider = 1 in pio_get_default_sm_config  in pio.h (#2863)

Add Clock Divider = 1 to documentation of pio_get_default_sm_config

src/rp2_common/hardware_pio/include/hardware/pio.h

diff --git a/src/rp2_common/hardware_pio/include/hardware/pio.h b/src/rp2_common/hardware_pio/include/hardware/pio.h
index dd111e1..7d0eff6 100644
--- a/src/rp2_common/hardware_pio/include/hardware/pio.h
+++ b/src/rp2_common/hardware_pio/include/hardware/pio.h
@@ -741,6 +741,7 @@
  *
  * Setting | Default
  * --------|--------
+ * Clock Divider | 1
  * Out Pins | 32 starting at 0
  * Set Pins | 0 starting at 0
  * In Pins | 32 starting at 0