message: Add troubleshooting section to README.md.
diff: ```javascript
  curl -L https://raw.githubusercontent.com/sumup/create-sumup-react-app/master/create-sumup-react-app.sh | bash -s -- {project-name}
  ```
  +
  +## Troubleshooting
  +
  +```
  +error eslint@5.0.1: The engine "node" is incompatible with this module. Expected version "^6.14.0 || ^8.10.0 || >=9.10.0".
  +error Found incompatible module
  +```
  +
  +Use a version of node that is compatible with ESLint. This is easy to accomplish with [nvm](https://github.com/creationix/nvm).
  