DOC-2462: TinyMCE 7.3 Release Documentation

[FarzadHayat]

Ticket: DOC-2462

Site: Staging branch

Changes:

• Finalised target branch containing all changes for TinyMCE 7.3 release.

Pre-checks:

• [x] Branch prefixed with feature/<version>/, hotfix/<version>/, staging/<version>/, or release/<version>/
• [x] modules/ROOT/nav.adoc has been updated (if applicable)
• [x] Files has been included where required (if applicable)
• [x] Files removed have been deleted, not just excluded from the build (if applicable)
• [x] Files added for New product features, and included a release note entry.

Review:

• [x] Documentation Team Lead has reviewed