Fix docs intro version for force auth for approvers

This feature was introduced in 12.0, not in 11.11.

doc/user/project/merge_requests/merge_request_approvals.md

@@ -294,6 +294,18 @@ enabling [**Prevent approval of merge requests by their committers**](#prevent-a
 1. Tick the checkbox **Prevent approval of merge requests by their committers**.
 1. Click **Save changes**.
 
+## Require authentication when approving a merge request **[STARTER]**
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab-ee/issues/5981) in [GitLab Starter](https://about.gitlab.com/pricing/) 12.0.
+
+You can force the approver to enter a password in order to authenticate who is approving the merge request by
+enabling **Require user password to approve**. This enables an Electronic Signature
+for approvals such as the one defined by [CFR Part 11](https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=11&showFR=1&subpartNode=21:1.0.1.1.8.3)):
+
+1. Navigate to your project's **Settings > General** and expand **Merge request approvals**.
+1. Tick the checkbox **Require user password to approve**.
+1. Click **Save changes**.
+
 ## Merge requests with different source branch and target branch projects
 
 If the merge request source branch and target branch belong to different