Update development instructions in readme

Author: oskarrough

.env-example

@@ -0,0 +1,3 @@
+FIREBASE_API_KEY="abc123"
+FIREBASE_AUTH_DOMAIN="abc123"
+FIREBASE_DATABASE_URL="abc123"

README.md

@@ -4,9 +4,17 @@ Public API to [Radio4000.com](https://radio4000.com).
 
 Documentation and examples can be found here [https://github.com/Internet4000/radio4000-api-docs](https://github.com/Internet4000/radio4000-api-docs).
 
-# Deployment
+## How to develop
 
-To deploy to staging, run `yarn deploy` or `npm run deploy`.  
-To deploy to production, deploy (to staging) and then run `now alias` (only works if you have now.sh permissions).
+- `git clone git@github.com:internet4000/radio4000-api.git`
+- `cd radio4000-api; cp .env-example .env` (and enter the real keys)
+- `yarn`
+- `yarn start`
 
-Peace
+## How to deploy
+
+To deploy to staging, run `yarn deploy`.
+
+To deploy to production, first `yarn deploy` and then `now alias` (you need access to the Internet4000 team on now.sh)
+
+Peace