Add readme.md

README.md

+# DS18B20 for CH Monitor
+
+This is a simple script written in PHP to submit the temperature read from a DS18B20 sensor to CH Monitor.
+
+## Setup
+
+You will need to setup the pi to add OneWire support.
+Start by adding the following line to `/boot/config.txt` at the very bottom:
+```
+dtoverlay=w1-gpio
+```
+
+Then edit `/etc/modules` and add the following 2 lines at the very bottom:
+```
+w1-gpio
+w1-therm
+```
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