Updated docker-compose snippet to a working one (#13196)

added 'bundle exec' before rake

.env.production.sample

@@ -33,7 +33,7 @@ LOCAL_DOMAIN=example.com
 # ALTERNATE_DOMAINS=example1.com,example2.com
 
 # Application secrets
-# Generate each with the `RAILS_ENV=production bundle exec rake secret` task (`docker-compose run --rm web rake secret` if you use docker compose)
+# Generate each with the `RAILS_ENV=production bundle exec rake secret` task (`docker-compose run --rm web bundle exec rake secret` if you use docker compose)
 SECRET_KEY_BASE=
 OTP_SECRET=
 
@@ -42,7 +42,7 @@ OTP_SECRET=
 # You should only generate this once per instance. If you later decide to change it, all push subscription will
 # be invalidated, requiring the users to access the website again to resubscribe.
 #
-# Generate with `RAILS_ENV=production bundle exec rake mastodon:webpush:generate_vapid_key` task (`docker-compose run --rm web rake mastodon:webpush:generate_vapid_key` if you use docker compose)
+# Generate with `RAILS_ENV=production bundle exec rake mastodon:webpush:generate_vapid_key` task (`docker-compose run --rm web bundle exec rake mastodon:webpush:generate_vapid_key` if you use docker compose)
 #
 # For more information visit https://rossta.net/blog/using-the-web-push-api-with-vapid.html
 VAPID_PRIVATE_KEY=