docs: remove instructions using ng update

`ng update` has been removed in #4628.

Close #4771

Author: filipesilva

README.md

@@ -114,15 +114,8 @@ Local project package:
 rm -rf node_modules dist # use rmdir on Windows
 npm install --save-dev @angular/cli@latest
 npm install
-ng update
 ```
 
-Running `ng update` will check for changes in all the auto-generated files created by `ng new` and allow you to update yours. You are offered four choices for each changed file: `y` (overwrite), `n` (don't overwrite), `d` (show diff between your file and the updated file) and `h` (help).
-
-Carefully read the diffs for each code file, and either accept the changes or incorporate them manually after `ng update` finishes.
-
-**The main cause of errors after an update is failing to incorporate these updates into your code**.
-
 You can find more details about changes between versions in [CHANGELOG.md](https://github.com/angular/angular-cli/blob/master/CHANGELOG.md).
 
 

docs/documentation/overview.md

@@ -44,7 +44,6 @@ End-to-end tests are run via [Protractor](https://angular.github.io/protractor/)
 
 ### Additional Commands
 * [ng new](new)
-* [ng update](update)
 * [ng serve](serve)
 * [ng generate](generate)
 * [ng test](test)