adding clarification on zone holds for ssl for saas

[mia303]

Documentation checklist

• The documentation style guide has been adhered to.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.

[holopin-bot]

Congratulations @mia303, the maintainer of this repository has issued you a holobyte! Here it is: https://holopin.io/holobyte/cmdq3x5fz371107iedr9yn3ti

This badge can only be claimed by you, so make sure that your GitHub account is linked to your Holopin account. You can manage those preferences here: https://holopin.io/account.
Or if you're new to Holopin, you can simply sign up with GitHub, which will do the trick!