Remove VSA duration median documentation

doc/user/analytics/value_stream_analytics.md

@@ -337,7 +337,8 @@ Feature.disable(:value_stream_analytics_create_multiple_value_streams)
 
 ## Days to completion chart
 
-> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/21631) in GitLab 12.6.
+> - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/21631) in GitLab 12.6.
+> - [Chart median line removed](https://gitlab.com/gitlab-org/gitlab/-/issues/235455) in GitLab 13.4.
 
 This chart visually depicts the total number of days it takes for cycles to be completed.
 
@@ -345,15 +346,6 @@ This chart uses the global page filters for displaying data based on the selecte
 group, projects, and timeframe. In addition, specific stages can be selected
 from within the chart itself.
 
-### Chart median line
-
-> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/36675) in GitLab 12.7.
-
-The median line on the chart displays data that is offset by the number of days selected.
-For example, if 30 days worth of data has been selected (for example, 2019-12-16 to 2020-01-15) the
-median line will represent the previous 30 days worth of data (2019-11-16 to 2019-12-16)
-as a metric to compare against.
-
 ### Disabling chart
 
 This chart is enabled by default. If you have a self-managed instance, an
@@ -363,9 +355,9 @@ administrator can open a Rails console and disable it with the following command
 Feature.disable(:cycle_analytics_scatterplot_enabled)
 ```
 
-## Type of work - Tasks by type chart
+## Type of work - Tasks by type chart **(PREMIUM)**
 
-> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/32421) in GitLab 12.10.
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/32421) in [GitLab Premium](https://about.gitlab.com/pricing/) 12.10.
 
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