extract feature toggles to its own file + document usage in README

Author: saljuama

README.md

@@ -3,3 +3,65 @@
 [![CircleCI](https://circleci.com/gh/saljuama/codebar-pairing-tool.svg?style=svg)](https://circleci.com/gh/saljuama/codebar-pairing-tool)
 
 See it in action: https://saljuama.github.io/codebar-pairing-tool
+
+## Development
+
+### Running the application locally
+
+```bash
+$ yarn start
+```
+
+### Running the tests
+
+#### Unit tests
+
+```bash
+$ yarn test
+```
+
+#### Functional tests
+
+This requires that the application is running locally
+
+```bash
+$ yarn test:e2e
+```
+
+### Working with Feature Toggles
+
+If we wanted to create a new toggle named `myToggle` with a default value of `false`, we would: 
+
+#### Adding a new toggle 
+Add the name, and the default value in the `src/config/featureToggles.js` file.
+```javascript
+export const featureToggles = {
+  myToggle: false
+}
+```
+
+It is recommended to create new toggles with a default value of `false` so new features developed under them are not 
+available to the users right away until the features are ready for it
+
+#### Accessing the value of a feature toggle
+```javascript
+import {useSelector} from 'react-redux'
+import {featureEnabled} from '..path-to-config-folder../config/togglesSlice' 
+
+const AnyComponent = () => {
+    const myToggleValue = useSelector(featureEnabled('myToggle')) // false
+    // rest of the component
+}
+```
+
+#### Overriding a toggle value
+With the querystring parameters: 
+* Local: after `yarn start` we can visit `http://localhost:3000?myToggle=true` 
+* In GH pages: visit `https://saljuama.github.io/codebar-pairing-tool?myToggle=true`
+
+#### Releasing and cleaning up
+To release a feature, or a change, hidden under a feature toggle, just go to the `src/config/featureToggles.js` file and
+change the value to `true`. 
+
+Once is verified that the feature is stable, and we will not need to turn the toggle off, we can start cleaning up the
+source code to remove the toggle usages and remove the toggle from the `src/config/featureToggles.js` file itself.

src/config/featureToggles.js

@@ -0,0 +1,3 @@
+export const featureToggles = {
+  csvFileDropzoneWithDnd: false
+}

src/config/store.js

@@ -1,8 +1,9 @@
 import {configureStore} from '@reduxjs/toolkit'
-import {togglesReducer, initialState as toggles} from './togglesSlice'
+import {togglesReducer} from './togglesSlice'
 import {configurationReducer, initialState as configuration} from '../app/configuration/configurationSlice'
 import {attendeesReducer, initialState as attendees} from '../app/pairingTool/attendees/attendeesSlice'
 import {pairingsReducer, initialState as pairings} from '../app/pairingTool/pairings/pairingsSlice'
+import {featureToggles as toggles} from './featureToggles'
 
 export const storeInitialState = {
   toggles,

src/config/togglesSlice.js

@@ -1,12 +1,9 @@
 import {createSlice} from '@reduxjs/toolkit'
-
-export const initialState = {
-  csvFileDropzoneWithDnd: false
-}
+import {featureToggles} from './featureToggles'
 
 const togglesSlice = createSlice({
   name: 'toggles',
-  initialState,
+  initialState: featureToggles,
   reducers: {
     overrideToggle: (state, action) => {
       if (action.payload.toggle in state)