drivers: w1: Ensure DQ pin is both input and output.

Driver did not work on ESP32c3, by specifying pin to be output and
input solve the issue. Improve documentation, to highlight that driver
is requiring open-drain support.

Signed-off-by: Fredrik Gihl <fgihl@hotmail.com>

dts/bindings/w1/zephyr,w1-gpio.yaml

@@ -19,6 +19,12 @@ description: |
     - w1 is pin 13 on gpio0. The gpio is active when the pin is high, is
       configured as an open-drain, and has a pull-up resistor.
 
+  Implementation details:
+    - Most drivers require the selected gpio to support open drain, this enables onewire
+      devices to lower the signal when the SOC set the signal high.
+    - Ensure pullup is strong enough (4.7K according to the specification). Standard pullup in
+      SOC are usually weak, and may not be strong enough.
+
 compatible: "zephyr,w1-gpio"
 
 include: [w1-master.yaml]