Flesh out README setup

README.md

@@ -1,16 +1,31 @@
 # Suri × Deploy to GitHub Pages
 
 You're viewing a template repository tailored for deploying Suri to
-[GitHub Pages](https://pages.github.com/).
+[GitHub Pages](https://pages.github.com/) with
+[GitHub Actions](https://docs.github.com/en/actions).
 
 What's Suri? Suri is your own link shortener that's easily deployed as a static
 site. No server-side hosting, serverless cloud functions, or database necessary.
 Head over to the main [`jstayton/suri`](https://github.com/jstayton/suri)
 repository to learn more, including additional deployment methods.
 
-## Install
-
-_TBD_
+## Setup
+
+1. Click the "Use this template" button above and then "Create a new
+   repository". Fill in the required details to create a new repository based on
+   this one.
+2. Go to the "Settings" of your new repository and head to the "Pages" section.
+   Under "Build and deployment", change the "Source" to "GitHub Actions".
+3. Go to the "Actions" of your new repository. There should be a workflow run
+   that likely failed because the previous step wasn't yet completed. Go ahead
+   and click into the workflow run and click the "Re-run jobs" button.
+4. Any commits to the `main` branch of your new repository will trigger a new
+   deploy. You can change this by editing
+   [`.github/workflows/deploy.yml`](./.github/workflows/deploy.yml), which is
+   the GitHub Actions workflow for building the site and deploying to GitHub
+   Pages.
+5. If you want to use a custom domain, follow GitHub's guide:
+   [Managing a custom domain for your GitHub Pages site](https://docs.github.com/en/pages/configuring-a-custom-domain-for-your-github-pages-site/managing-a-custom-domain-for-your-github-pages-site).
 
 ## Manage Links
 
@@ -30,8 +45,8 @@ and the value is the target URL. Keys can be as short or as long as you want,
 using whatever mixture of characters you want. `/` is a special entry for
 redirecting the root path.
 
-Go ahead and make an edit, then commit and push to your repository. GitHub Pages
-should automatically build and deploy your change. That's it!
+Go ahead and make an edit, then commit and push to your repository. GitHub
+Actions should automatically build and deploy your change. That's it!
 
 ## Config