Follow-up from "Docs: add product badges to docs"

The following discussion from !5381 (merged) should be addressed:

• @brodock started a discussion: (+1 comment)

  This link is missing a definition on footer.

What

Add a missing link to the Jira doc:

> [Introduced][ee-2381] in [GitLab Premium][eep] 10.0.

It's missing [ee-2381].