docs(build): documented environment support

ISSUES CLOSED: NationalBankBelgium#50

docs/ENVIRONMENTS.md

@@ -0,0 +1,43 @@
+# Environments support 
+
+## Environment.ts
+
+In the `src/environments/model.ts` is provided the Environment interface as follows
+
+```
+...
+export interface Environment {
+	production: boolean;
+	hmr: boolean;
+	...
+```
+
+`production`, which is a boolean, will specify is your application runs under a production environment, 
+while `hmr` will indicate if it runs under a Hot Module Replacement environment. 
+
+This interface will then be defined by default in `src/environments/environment.ts`: 
+```
+...
+export const environment: Environment = {
+	production: false,
+	hmr: false,
+	showDevModule: true,
+	...
+```
+
+## How to find out which environment is your application is currently using? 
+
+All you have to do is to import in your app.module.ts file the environment.ts constant 
+```
+import { environment } from "../environments/environment";
+```
+
+This way, you will be able to programmatically determine which environment is used in your app
+with simple checks, as follows: 
+
+```
+environment.production 
+// if the output of this line is true, we are in production environment. 
+// Otherwise, we are in hmr environment. 
+```
+