DOCS-1831 - Clarify certificate of destruction note in Deletion Requests

[JV0812]

Purpose of this pull request

This pull request clarifies the certificate-of-destruction note on the Deletion Requests doc. A Genesys customer flagged the existing wording as ambiguous — it read as if a certificate might be available through this self-service feature under some circumstances. Per Aman Singla's clarification in Slack, the certificate only applies to complete account data destruction at the end of a subscription and is never provided through this feature, regardless of deletion scope.

Select the type of change

• Minor Changes - Typos, formatting, slight revisions
• Update Content - Revisions, updating sections
• New Content - New features, sections, pages, tutorials
• Site and Tools - .clabot, version updates, maintenance, dependencies, new packages for the site (Docusaurus, Gatsby, React, etc.)

Ticket (if applicable)

https://sumologic.atlassian.net/browse/DOCS-1831