Copyedit burndown chart docs

doc/workflow/milestones.md

@@ -27,14 +27,33 @@ special options available when filtering by milestone:
   date less than today. Note that this can return results from several
   milestones in the same project.
 
-## Burndown (EE-Only)
+## Burndown charts
 
-A burndown chart is available for every project milestone that has a set start date and a set due date. It is located on the project milestone page. It indicates project progress throughout that milestone (for issues that have that milestone assigned to it). In particular, it shows how many issues were or are still open for a given day in the milestone period. Since GitLab only tracks when an issue was last closed (and not its full history) the chart assumes that issue was open on days prior to that date. Reopened issues are considered as open on one day after they were closed. The burndown chart can also be toggled to display the cumulative open issue weight for a given day. When using this feature, make sure your weights have been properly assigned, since an open issue with no weight adds zero to the cumulative value.
+> [Introduced][ee-1540] in GitLab Enterprise Edition 9.1 and is available for
+  [Enterprise Edition Starter][ee] users.
+
+A burndown chart is available for every project milestone that has a set start
+date and a set due date and is located on the project's milestone page.
+
+It indicates the project's progress throughout that milestone (for issues that
+have that milestone assigned to it). In particular, it shows how many issues
+were or are still open for a given day in the milestone period. Since GitLab
+only tracks when an issue was last closed (and not its full history), the chart
+assumes that issue was open on days prior to that date. Reopened issues are
+considered as open on one day after they were closed.
+
+The burndown chart can also be toggled to display the cumulative open issue
+weight for a given day. When using this feature, make sure your weights have
+been properly assigned, since an open issue with no weight adds zero to the
+cumulative value.
 
 ![burndown chart](milestones/burndown_chart.png)
 
-Closed or reopened issues prior to GitLab 9.1 version won't have a `closed_at` value, so the burndown chart considers it as closed on the milestone `start_date`. In that case a warning will be displayed.
+Closed or reopened issues prior to GitLab 9.1 version won't have a `closed_at`
+value, so the burndown chart considers it as closed on the milestone `start_date`.
+In that case, a warning will be displayed.
 
 ![burndown chart warning](milestones/burndown_warning.png)
 
-
+[ee-1540]: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1540
+[ee]: https://about.gitlab.com/gitlab-ee