Updates webflow configuration

[sbastn]

Fixes #94. This PR updates the one-click service for Webflow.

Based on their documentation https://university.webflow.com/article/connecting-a-custom-domain#update-the-dns, the one-click service has been updated to:

1. Prompt for two A records
2. Prompt for one CNAME record

👀 How to test this

1. Checkout this branch.
2. From the DNSimple app, point the services rake file to your local repo.

# File: lib/tasks/services.rake
5     sh("git clone /Users/me/projects/dnsimple/dnsimple-services tmp/dnsimple-services")

3. From the DNSimple app, execute rake services:import
4. From the DNSimple app, add the Webflow one-click service to any domain. You should be prompted to enter two A records for the root/apex, and a CNAME record that will be added to the "www" subdomain.
5. On /services, you should see Webflow listed

[dallasread]

👍 Matches webflow documentation and creates expected records.

[san983]

✅