Update README.md

Author: milesburton

README.md

@@ -18,11 +18,11 @@ A robust and feature-complete Arduino library for Maxim Temperature Integrated C
 |  device    |   power   |  notes  |
 |:-----------|:---------:|:--------|
 |  DS18B20   |   3-5 V   |  the reference
-|  DS18S20   |   3-5 V   |  9 bit only, ⚠️ Known issues with this series
+|  DS18S20   |   3-5 V   |  9 bit only, ⚠️    Known issues with this series
 |  DS1822    |   3-5 V   |
 |  DS1820    |   5 V     |  9 bit only
-|  MAX31820  |   3 V     |
-|  MAX31850/1  |   3-3.7V  |  thermocouple
+|  MAX31820  |   3 V ⚠️    |
+|  MAX31850/1  |   3-3.7V ⚠️  |  thermocouple
 
 ## 🚀 Installation