chore: update .env.example

.env.example

@@ -4,6 +4,7 @@ DATABASE_URL=<your-neon-database-url>
 # Authentication
 CLERK_SECRET_KEY=<your-clerk-secret-key>
 NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY=<your-clerk-publishable-key>
+
 # You don't need to change these, just copy them over into your `.env` file.
 NEXT_PUBLIC_CLERK_SIGN_IN_URL='/sign-in'
 NEXT_PUBLIC_CLERK_SIGN_UP_URL='/sign-up'
@@ -12,4 +13,7 @@ NEXT_PUBLIC_CLERK_SIGN_UP_FORCE_REDIRECT_URL='/app'
 
 # Upstash Redis
 UPSTASH_REDIS_REST_URL=<your-upstash-rest-url>
-UPSTASH_REDIS_REST_TOKEN=<your-upstash-rest-token>
+UPSTASH_REDIS_REST_TOKEN=<your-upstash-rest-token>
+
+# Resend
+RESEND_API_KEY=<your-resend-api-key>