Re-structure Analytics documentation index

Previously the Analytics documentation index was built around the
Analytics Workspace concept. It did not sufficiently explain features
located outside the Workspace. Plus, we are moving away from the
Workspace concept anyway. This re-structures the Analytics
documentation index into 3 sections: instance (Workspace), group and
project levels. The Analytics features available are explained.

doc/user/analytics/index.md

-# Analytics workspace
+# Analytics
+
+## Analytics workspace
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/12077) in GitLab 12.2.
 
@@ -6,27 +8,30 @@ The Analytics workspace will make it possible to aggregate analytics across
 GitLab, so that users can view information across multiple projects and groups
 in one place.
 
-To access the centralized analytics workspace, enable at least
-[one of the features](#available-analytics) under the workspace.
+To access the Analytics workspace, click on **More > Analytics** in the top navigation bar.
 
-Once enabled, click on **Analytics** from the top navigation bar.
+## Group-level analytics
 
-## Available analytics
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/195979) in GitLab 12.8.
 
-From the centralized analytics workspace, the following analytics are available:
+The following analytics features are available at the group level:
 
-- [Code Review Analytics](code_review_analytics.md). **(STARTER)**
-- [Value Stream Analytics](value_stream_analytics.md), enabled with the `cycle_analytics`
+- [Contribution](../group/contribution_analytics/index.md). **(STARTER)**
+- [Insights](../group/insights/index.md). **(ULTIMATE)**
+- [Issues](../group/issues_analytics/index.md). **(PREMIUM)**
+- [Productivity](productivity_analytics.md), enabled with the `productivity_analytics`
   [feature flag](../../development/feature_flags/development.md#enabling-a-feature-flag-in-development). **(PREMIUM)**
-- [Productivity Analytics](productivity_analytics.md), enabled with the `productivity_analytics`
+- [Value Stream](value_stream_analytics.md), enabled with the `cycle_analytics`
   [feature flag](../../development/feature_flags/development.md#enabling-a-feature-flag-in-development). **(PREMIUM)**
 
-NOTE: **Note:**
-Project-level Value Stream Analytics are still available at a project's **Project > Value Stream Analytics**.
-
-## Other analytics tools
+## Project-level analytics
 
-In addition to the tools available in the Analytics workspace, GitLab provides:
+The following analytics features are available at the project level:
 
-- [Contribution analytics](../group/contribution_analytics/index.md). **(STARTER)**
-- [Issue analytics](../group/issues_analytics/index.md). **(PREMIUM)**
+- [CI/CD](../../ci/pipelines/index.md#pipeline-success-and-duration-charts). **(STARTER)**
+- [Code Review](code_review_analytics.md). **(STARTER)**
+- [Insights](../group/insights/index.md). **(ULTIMATE)**
+- [Issues](../group/issues_analytics/index.md). **(PREMIUM)**
+- Repository. **(STARTER)**
+- [Value Stream](value_stream_analytics.md), enabled with the `cycle_analytics`
+  [feature flag](../../development/feature_flags/development.md#enabling-a-feature-flag-in-development). **(STARTER)**