README suggestion: tell me what "ng deploy" does

[jessitron]

Is your feature request related to a problem? Please describe.
I'm a first-time Netlify user. (And pretty new to Angular.) I deployed my repo once as a static site, then generated a new angular project inside it.
When googling "netlify angular," I find this repository. But it doesn't help me understand Netlify or Angular or what it is I should expect.

Describe the solution you'd like
When reading the README, I would like it to say what happens on "ng deploy" that doesn't on a "git push."
Does it change the configuration of my site on Netlify? does it perform a local build or one on Netlify? Is this deploy going to be overridden when I push to main?

Describe alternatives you've considered
I got here from this article which has the same problem, I don't understand what the builder does: https://www.netlify.com/blog/2019/09/17/using-the-angular-builder-for-netlify/ (I'd leave an issue there instead, if that were as easy.)

Additional context
Thanks for your work creating and maintaining this.