mention vercel env var setup

Author: gregrickaby

README.md

@@ -126,7 +126,9 @@ yarn
 
 **Step 4: Setup ENV Variables**
 
-ENV variables are like constants in `wp-config.php`. Copy the sample ENV file, then add your credentials:
+ENV variables are like constants in `wp-config.php`. They're required in order for authentication and 3rd party services to work.
+
+Copy the [sample ENV file](https://github.com/WebDevStudios/nextjs-wordpress-starter/blob/staging/.env.sample), then modify it to match your credentials:
 
 ```bash
 cp .env.sample .env
@@ -138,28 +140,40 @@ cp .env.sample .env
 
 <details>
 
-The following steps require A) access to a Vercel account and B) assumes the ENV vars are already set up on Vercel. If you need access to the WDS Team account on Vercel, please reach out to Greg.
+The preferred workflow is to add ENV variables to Vercel first, then pull them down.
+
+**Step 1: Add ENV vars to Vercel**
+
+Go to:
+
+```text
+Your Project --> Settings --> Environment Variables
+```
+
+![vercel settings](https://dl.dropbox.com/s/7ljvynnez0c5q8y/Screen%20Shot%202021-01-29%20at%2014.07.58.png?dl=0)
 
-**Step 1: Install the [Vercel CLI](https://vercel.com/download)**
+**Step 2: Install the [Vercel CLI](https://vercel.com/download)**
 
 ```bash
 npm i -g vercel
 ```
 
-**Step 2: Initialize Vercel**
+**Step 3: Initialize Vercel**
+
+Answer the questions in the command line when prompted.
 
 ```bash
 vercel init
 ```
 
-Answer the questions in the command line when prompted.
-
-**Step 3: Pull down the ENV variables**
+**Step 4: Pull down the ENV variables**
 
 ```bash
 vercel env pull
 ```
 
+Now Next.js has what it needs to talk to 3rd party services.
+
 </details>
 
 ---
@@ -195,11 +209,11 @@ define('PREVIEW_SECRET_TOKEN', 'ANY_RANDOM_STRING');
 
 **Step 4: Start the `nextjs-wp` site**
 
-**Note:** Make sure your local URL matches the `LOCAL_WORDPRESS_API_URL` in the frontend `.env` file!
-
 ### Enable Previews
 
-To enable previews, you'll need both a `PREVIEW_SECRET_TOKEN` constant in `wp-config.php` and `WORDPRESS_PREVIEW_SECRET` ENV variable in `.env`. The token can be any random string so long as they match.
+To enable previews, you'll need both a `PREVIEW_SECRET_TOKEN` constant in `wp-config.php` and `WORDPRESS_PREVIEW_SECRET` ENV variable in `.env`.
+
+The token can be any random string as long as they match.
 
 ---