Updated admin targets page with the new link targets

[AaronSpringut]

Background

We're adding some new link extension targets while migrating the existing link extensions to the CLI. These need to be documented

Solution

Added a new section to the admin extension static docs that outlines what the targets are and where they appear in the admin.

Checklist

• I have 🎩'd these changes
• I have updated relevant documentation

[alfonso-noriega]

some targets need to be removed