ICSHWI-7227: updated README

README.md

-# Getting Started with Create React App
+# CCCE deployment tool web UI
+
+This project is meant to be the web User Interface for the CCCE Deployment tool. The project is written in ReactJS.
+
+## Developing environment
+* NodeJS and npm
+* Docker (if want to run backend locally for test purposes)
+* IDE for JavaScript developement (e.g. Visual Studio Code)
+
+(For developing purposes it is suggested to use _Node Version Manager_ [NVM] which makes easy to change between different Node versions).
+* Windows: https://github.com/coreybutler/nvm-windows
+* Mac/Linux: https://github.com/nvm-sh/nvm
+
+### Required versions
+* Node: v14.10+
+* npm: v6.10+
+
+## Local development setup
+For being able to run the backend, and frontend application on the same machine (locally) a proxy has been set in the project!
+If you <ins>don't want to run</ins> the backend server, and frontend on the same machine, or have different settings, please adjust the `package.json` at the following line:
+`"proxy": "http://localhost:8080"`
+
+### Environment Variables
+Environment variables are stored in `.env` files.
+Precedency of environment variable files are (files on the left have more priority than files on the right):
+* npm start: `.env.development.local`, `.env.local`, `.env.development`, `.env`
+* npm run build: `.env.production.local`, `.env.local`, `.env.production`, `.env`
+* npm test: `.env.test.local`, `.env.test`, `.env` (note .env.local is missing)
+
+All environment variables start with `REACT_APP_` prefix.
+
+| Environment variable     | Description |
+| -------------------------|-------------|
+| SERVER_ADDRESS        | The backend server base URL _(host:port)_ (if backend server is running natively on the same host as the UI then the value has to be empty, and proxy has to be set!)|
+| API_BASE_ENDPOINT     | The context path of the application's REST API _(e.g. /ccce-api)_ |
+| TOKEN_RENEW_INTERVAL  | Time interval to renew JWT auth token _(in milliseconds)_ | 
+
+## Useful links to start developing in ReactJS
 
 This project was bootstrapped with [Create React App](https://github.com/facebook/create-react-app).
 
@@ -47,24 +84,24 @@ To learn React, check out the [React documentation](https://reactjs.org/).
 
 ### Code Splitting
 
-This section has moved here: [https://facebook.github.io/create-react-app/docs/code-splitting](https://facebook.github.io/create-react-app/docs/code-splitting)
+[https://facebook.github.io/create-react-app/docs/code-splitting](https://facebook.github.io/create-react-app/docs/code-splitting)
 
 ### Analyzing the Bundle Size
 
-This section has moved here: [https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size](https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size)
+[https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size](https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size)
 
 ### Making a Progressive Web App
 
-This section has moved here: [https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app](https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app)
+[https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app](https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app)
 
 ### Advanced Configuration
 
-This section has moved here: [https://facebook.github.io/create-react-app/docs/advanced-configuration](https://facebook.github.io/create-react-app/docs/advanced-configuration)
+[https://facebook.github.io/create-react-app/docs/advanced-configuration](https://facebook.github.io/create-react-app/docs/advanced-configuration)
 
 ### Deployment
 
-This section has moved here: [https://facebook.github.io/create-react-app/docs/deployment](https://facebook.github.io/create-react-app/docs/deployment)
+[https://facebook.github.io/create-react-app/docs/deployment](https://facebook.github.io/create-react-app/docs/deployment)
 
 ### `npm run build` fails to minify
 
-This section has moved here: [https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify](https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify)
+[https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify](https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify)