upgrade application to angular 11 code example

Example 1: ng update @angular/core @angular/cli

npm uninstall -g angular-cli
npm install -g @angular/cli@latest

Example 2: angular 8 to 9

First, update to the latest version of 8
ng update @angular/cli@8 @angular/core@8

Then, update to 9
ng update @angular/cli @angular/core