Earth Hero Climate Action app volunteer opportunity (#227)

Add Earth Hero climate action app volunteer opportunity.

Author: EarthHeroOrg

README.md

@@ -375,7 +375,8 @@ The world is simultaneously underwater and on fire, and people want to know what
 - [Citizens Climate Lobby](https://citizensclimatelobby.org/) - If you’re an English, economics or poly sci major, you probably should consider volunteering for Citizens’ Climate Lobby, an organization focused on confronting climate change through policy.
 - [Clean Trails](https://www.cleantrails.org/join) - Step by step, and little by little, our aim is to eliminate waste on all the trails that grace our public lands. We believe we can do that in a positive and proactive manner by educating, encouraging, and reconnecting outdoor users to our pristine places.
 - [ClimateAction.Tech](https://climateaction.tech/) - A global community of tech professionals using our skills, expertise and platforms to support solutions to the climate crisis. The mission is to empower technology professionals to play our part — to meet, discuss, learn and take climate action.
-- [ClimatePrediction.net](https://www.climateprediction.net/) - The world’s largest climate modelling experiment. Evidence of how our climate is changing is vital to reducing greenhouse gas emissions. Help discover how the climate could look by running software on your computer.
+- [ClimatePrediction.net](https://www.climateprediction.net/) - The world’s largest climate modelling experiment. Evidence of how our climate is changing is vital to reducing greenhouse gas emissions.  Help discover how the climate could look by running software on your computer.
+- [Earth Hero Climate Action App](https://www.earthhero.org/get-involved/) - Join the volunteer team behind the free climate action app that makes it easy for people to act on climate change. Made up of developers, designers, researchers, writers, marketers, translators, and project managers from around the world.
 - [Economists for Future](https://econ4future.org/) - Economists for Future growing movement of people committed to galvanising the economics community behind addressing the greatest challenge of our day. If the discipline which dedicates itself to studying the economy cannot sufficiently engage in the economic transformation that the climate science requires, then who else can be expected to do this?
 - [Extinction Rebellion](https://rebellion.global/) - Extinction Rebellion is a decentralised, international and politically non-partisan movement using non-violent direct action and civil disobedience to persuade governments to act justly on the Climate and Ecological Emergency.
 - [Eyes of the Reef Hawai'i](https://eorhawaii.org/2013/07/18/become-a-member/) - Network to inform, engage and train people to identify coral bleaching, disease and invasive species outbreaks. They have a broad outreach program that helps to provide critical training for rapid response monitoring and stewardship of precious marine resources.