Fix installation instructions link in the README (ansible#24754)

* Fix the installation instructions link in the README

The original linked page (Getting started) assumed the user already had an installed system, which clearly was not the intention of the link.
So I replaced it with a link to the installation instructions, and removed the quick advice. The installation instructions are well structured and complete.

* Change to https

Links to ansible.com should end up over https
Seem to be missing the http -> https redirect from the docs site, I'll poke someone about that

Author: dagwieers

README.md

@@ -11,9 +11,7 @@ Read the documentation and more at https://ansible.com/
 
 Many users run straight from the development branch (it's generally fine to do so), but you might also wish to consume a release.
 
-You can find instructions [here](https://docs.ansible.com/intro_getting_started.html) for a variety of platforms.
-
-If you want to download a tarball of a release, go to [releases.ansible.com](https://releases.ansible.com/ansible), though most users use `yum` (using the EPEL instructions linked above), `apt` (using the PPA instructions linked above), or `pip install ansible`.
+You can find instructions [here](https://docs.ansible.com/ansible/intro_installation.html) for a variety of platforms.
 
 Design Principles
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