Link main README installation to storefront docs

The storefront README is the canonical install path; avoid duplicating
outdated instructions in the root README.
Fixes #6516

Author: SiddharthGautam040

README.md

@@ -84,37 +84,9 @@ Begin by making sure you have
 required for Paperclip. (You can install it using [Homebrew](https://brew.sh) if
 you're on a Mac.)
 
-To add Solidus, begin with a newly created Rails application with its database.
+To install Solidus with the current storefront, follow the instructions in
+[storefront/README.md](storefront/README.md).
 
-```bash
-rails new my_store
-```
-
-> [!CAUTION]
-> Due to [a bug in `sprockets-rails`](https://github.com/rails/sprockets-rails/pull/546) we need to manually add the sprockets manifest into the generated rails app **before** running any rails commands inside the rails app folder.
-
-```bash
-mkdir -p my_store/app/assets/config
-cat <<MANIFEST > my_store/app/assets/config/manifest.js
-//= link_tree ../images
-//= link_directory ../javascripts .js
-//= link_directory ../stylesheets .css
-MANIFEST
-```
-
-### Installing Solidus
-
-In your application's root folder run:
-
-```bash
-bundle add solidus
-bin/rails g solidus:install
-```
-
-> [!NOTE]
-> Please make sure to generate the sprockets manifest before running the `solidus:install` generator.
-
-And follow the prompt's instructions.
 ### Accessing Solidus Store
 
 Start the Rails server with the command: