Update cancel-subscription.mdx

[mbbl]

Added adapted info from Macro: Billing > Moved domain does not cancel plan and account was invoiced

Furthermore, please note that changing the DNS on your domain name does not cancel your account, or your active subscription plans. The system waits for a manual cancellation of the subscriptions plans, since there are times that the owner of a domain name's DNS is required to take action to change it back because they did not intend to remove their account.  

You will receive a notification regarding the DNS change; however, that does not indicate the cancellation of your subscription plans.

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• Is there a changelog entry (guidelines)? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds, the Discord, and X.
• 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• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
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