docs(@angular/cli): update story for global lib to show correct bootstrap4

configuration

- update bootstrap4 url to point to correct page
- remove tether import in .angular-cli.json
- add umd version popper.js import in .angular-cli.json instead of tether

Closes angular#7584

Author: adityaparab

docs/documentation/stories/global-lib.md

@@ -4,21 +4,23 @@ Some javascript libraries need to be added to the global scope, and loaded as if
 they were in a script tag. We can do this using the `apps[0].scripts` and
 `apps[0].styles` properties of `.angular-cli.json`.
 
-As an example, to use [Bootstrap 4](http://v4-alpha.getbootstrap.com/) this is
+As an example, to use [Bootstrap 4](https://getbootstrap.com/docs/4.0/getting-started/introduction/) this is
 what you need to do:
 
 First install Bootstrap from `npm`:
 
 ```bash
-npm install bootstrap@next
+npm install jquery --save
+npm install popper.js --save
+npm install bootstrap@next --save
 ```
 
 Then add the needed script files to `apps[0].scripts`:
 
 ```json
 "scripts": [
-  "../node_modules/jquery/dist/jquery.js",
-  "../node_modules/tether/dist/js/tether.js",
+  "../node_modules/jquery/dist/jquery.slim.js",
+  "../node_modules/popper.js/dist/umd/popper.js",
   "../node_modules/bootstrap/dist/js/bootstrap.js"
 ],
 ```