update ionic code example

Example 1: ionic cli

$ npm install -g @ionic/cli

Example 2: How To Update ionic

npm uninstall -g ionic 
npm install -g ionic

Example 3: how to update angular core in ionic

npm i @ionic/angular@latest
npm i zone.js@~0.9.1
npm i @angular/core@"~8.x.x"
npm i @ionic/angular-toolkit@latest
npm i codelyzer@latest
npm remove @angular/http
ng update @angular/core @angular/cli --allow-dirty