Add ErriezMHZ19B submodule

Author: Erriez

.gitmodules

@@ -61,3 +61,6 @@
 [submodule "libraries/ErriezTTP229TouchKeypad"]
 	path = libraries/ErriezTTP229TouchKeypad
 	url = https://github.com/Erriez/ErriezTTP229TouchKeypad
+[submodule "libraries/ErriezMHZ19B"]
+	path = libraries/ErriezMHZ19B
+	url = https://github.com/Erriez/ErriezMHZ19B

README.md

@@ -16,6 +16,13 @@ git submodule update --recursive
 Move the libraries/* to your Arduino/libraries/ directory
 ```
 
+### [MH-Z19B CO2 Sensor](https://github.com/Erriez/ErriezMHZ19B) [![Build Status](https://travis-ci.org/Erriez/ErriezMHZ19B.svg?branch=master)](https://travis-ci.org/Erriez/ErriezMHZ19B)
+
+This is a MH-Z19B CO2 sensor library for Arduino with a small footprint. Hardware and software serial supported.
+
+[![ErriezMHZ19B](https://raw.githubusercontent.com/Erriez/ErriezMHZ19B/master/extras/MHZ19B.png)](https://github.com/Erriez/ErriezMHZ19B)
+
+
 ### [INA219 DC Power Sensor](https://github.com/Erriez/ErriezINA219) [![Build Status](https://travis-ci.org/Erriez/ErriezINA219.svg?branch=master)](https://travis-ci.org/Erriez/ErriezINA219)
 
 INA219 I2C/SMB DC Voltage/Current/Power sensor.