campaigns: dead link on the create campaign page

Created by: LawnGnome

Quoting Slack:

On the create campaign page Want more help? See campaigns documentation. links to the current instance version docs at user/campaigns (page not found) for hashicorp at v3.23. Reproducible on demo.sourcegraph.com - it points here >https://docs.sourcegraph.com/@v3.23.0/user/campaigns The code looks like it has the correct path: https://sourcegraph.com/github.com/sourcegraph/[email protected]/-/blob/client/web/src/enterprise/campaigns/create/CreateCampaignPage.tsx#L99 (edited)