Remove Overview header from pages

doc/user/project/issue_board.md

@@ -8,8 +8,6 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/5554) in [GitLab 8.11](https://about.gitlab.com/releases/2016/08/22/gitlab-8-11-released/#issue-board).
 
-## Overview
-
 The GitLab Issue Board is a software project management tool used to plan,
 organize, and visualize a workflow for a feature or product release.
 It can be used as a [Kanban](https://en.wikipedia.org/wiki/Kanban_(development)) or a

doc/user/project/issues/multiple_assignees_for_issues.md

@@ -8,8 +8,6 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/1904) in [GitLab Starter 9.2](https://about.gitlab.com/releases/2017/05/22/gitlab-9-2-released/#multiple-assignees-for-issues).
 
-## Overview
-
 In large teams, where there is shared ownership of an issue, it can be difficult
 to track who is working on it, who already completed their contributions, who
 didn't even start yet.

doc/user/project/labels.md

@@ -6,8 +6,6 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 # Labels
 
-## Overview
-
 As your count of issues, merge requests, and epics grows in GitLab, it's more and more challenging
 to keep track of those items. Especially as your organization grows from just a few people to
 hundreds or thousands. This is where labels come in. They help you organize and tag your work

doc/user/project/milestones/burndown_charts.md

@@ -14,8 +14,6 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 >   value, so the burndown chart considers them as closed on the milestone
 >  `start_date`. In that case, a warning will be displayed.
 
-## Overview
-
 Burndown Charts are visual representations of the progress of completing a milestone.
 
 ![burndown chart](img/burndown_chart.png)

doc/user/project/milestones/index.md

@@ -7,8 +7,6 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 # Milestones
 
-## Overview
-
 Milestones in GitLab are a way to track issues and merge requests created to achieve a broader goal in a certain period of time.
 
 Milestones allow you to organize issues and merge requests into a cohesive group, with an optional start date and an optional due date.

doc/user/project/service_desk.md

@@ -10,8 +10,6 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 > - [Moved](https://gitlab.com/gitlab-org/gitlab/-/issues/214839) to [GitLab Starter](https://about.gitlab.com/pricing/) in 13.0.
 > - [Moved](https://gitlab.com/gitlab-org/gitlab/-/issues/215364) to [GitLab Core](https://about.gitlab.com/pricing/) in 13.2.
 
-## Overview
-
 Service Desk is a module that allows your team to connect directly
 with any external party through email right inside of GitLab; no external tools required.
 An ongoing conversation right where your software is built ensures that user feedback ends