docs(@schematics/angular): update code scaffolding doc to with ng generate --help

[MrJithil]

PR Checklist

Please check to confirm your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular-cli/blob/main/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?
Improve the Code scaffolding section.

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Code scaffolding section is updated a while ago and new commands associated with ng generate is not included. Only a subset of available schematics is documented in this section.

Issue Number: #28059

What is the new behavior?

This PR updates the code scaffolding section to inform users about the various commands available with ng generate, such as ng generate component.

Since the list of commands may evolve in the future, it's best to guide developers to use the --help option with generate. The documentation is now rewritten to highlight the use of ng generate --help for accessing the most up-to-date list of commands.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[alan-agius4]

LGTM, thanks for your contribution

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