DOC-2392: Re-write of `editor-plugin-version.adoc` page.

[kemister85]

Ticket: DOC-2392

Site: Staging branch

Changes:

• Remove list of plugins versions from document.
• Remove mention of the ability to specify plugin versions when loading from Cloud.
• Added new admon for important message for placement of script tags.

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:

• [ ] Documentation Team Lead has reviewed