Update GPIO docs (digital.rst) (#656)

Author: sstaub

docs/digital.rst

@@ -6,6 +6,14 @@ Board-Specific Pins
 The Raspberry Pi Pico RP2040 chip supports up to 30 digital I/O pins,
 however not all boards provide access to all pins.
 
+Input Modes
+-----------
+The Raspberry Pi Pico has 3 Input modes settings for use with `pinMode`: `INPUT`, `INPUT_PULLUP` and `INPUT_PULLDOWN`
+
+Output Modes (Pad Strength)
+---------------------------
+The Raspberry Pi Pico has the ability to set the current that a pin (actually the pad associated with it) is capable of supplying. The current can be set to values of 2mA, 4mA, 8mA and 12mA. By default, on a reset, the setting is 4mA. A `pinMode(x, OUTPUT)`, where `x` is the pin number, is also the default setting. 4 settings have been added for use with `pinMode`: `OUTPUT_2MA`, `OUTPUT_4MA`, which has the same behavior as `OUTPUT`, `OUTPUT_8MA` and `OUTPUT_12MA`.
+
 Tone/noTone
 -----------
 Simple square wave tone generation is possible for up to 8 channels using

docs/pins.rst

@@ -60,8 +60,3 @@ it use a non-default pinout with a simple call
         SPI.setCS(5);
         SD.begin(5);
     }
-
-Pad Strength
-============
-
-The Raspberry Pi Pico has the ability to set the current that a pin (actually the pad associated with it) is capable of supplying. The current can be set to values of 2mA, 4mA, 8mA and 12mA. By default, on a reset, the setting is 4mA. A `pinMode(x, OUTPUT)`, where `x` is the pin number, is also the default setting. 4 settings have been added for use with `pinMode`: `OUTPUT_2MA`, `OUTPUT_4MA`, which has the same behavior as `OUTPUT`, `OUTPUT_8MA` and `OUTPUT_12MA`.