TINYDOC-3560: TinyMCE 8.8.1 Release Documentation.

[kemister85]

Ticket: TINYDOC-3560

Site: Staging branch

Pre-checks:

• Branch is correctly prefixed:
• modules/ROOT/nav.adoc has been updated (if applicable).
• Files have been included where required (if applicable).
• Files removed have been deleted, not just excluded from the build (if applicable).
• Files added for New product features include a release note entry.
• Major or minor version changes have updated the supported-versions.adoc table.
• Build passes without console errors, warnings, or issues.

Review:

• Documentation Team Lead has reviewed.