docs: update installation instructions

add `moment` as a dependency. 

Also remove note regarding TypeScript 1.8, as it is no longer relevant for Angular 5+ users.

close #194

README.md

@@ -11,18 +11,18 @@ For an Angular 2 / 4 version, please install [angular2-moment](https://npmjs.org
 Installation
 ------------
 
-`npm install --save ngx-moment`
+```bash
+npm install --save moment ngx-moment
+```
 
-If you use typescript 1.8, and [typings](https://github.com/typings/typings), you may also need to install typings for moment.js:
+or if you use yarn:
 
-`typings install --save moment`
+```bash
+yarn add moment ngx-moment
+```
 
 ### For System.js users:
 
-First you need to install moment:
-
-`npm install moment --save`
-
 Don't forget to update your systemjs.config.js:
 
 ```