Update UX for [Add to KB] command

[shanelle627]

Current Behavior: When you add [Add to KB [tag]] /{content-to-be-added}, it will show a little notification that goes away when the content is added and then it goes back to showing the previous command. If you've navigated away from Lightrail, it's not clear that the content has been added. Desired Behavior: When you add [Add to KB [tag]] /{content-to-be-added}, make the notification sticky that the content has been added and ideally show the previous command in the history above like