Add tier to docs for instance Analytics features

Previously the documentation for the 3 instance-level analytics features
did not explain which tier they are available in. This notes the tier
both on the index page and the 3 individual feature pages.

doc/user/admin_area/analytics/dev_ops_report.md

@@ -4,7 +4,7 @@ group: unassigned
 info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
 ---
 
-# DevOps Report
+# DevOps Report **(CORE)**
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/30469) in GitLab 9.3.
 > - [Renamed from Conversational Development Index](https://gitlab.com/gitlab-org/gitlab/-/issues/20976) in GitLab 12.6.

doc/user/admin_area/analytics/index.md

@@ -12,6 +12,6 @@ Administrators have access to instance-wide analytics, as shown in **Admin Area
 
 There are several kinds of statistics:
 
-- [DevOps Report](dev_ops_report.md): Provides an overview of your entire instance's feature usage.
-- [Instance Statistics](instance_statistics.md): Shows how much data your instance contains, and how that is changing.
-- [User Cohorts](user_cohorts.md): Display the monthly cohorts of new users and their activities over time.
+- [DevOps Report](dev_ops_report.md): Provides an overview of your entire instance's feature usage. **(CORE)**
+- [Instance Statistics](instance_statistics.md): Shows how much data your instance contains, and how that is changing. **(CORE)**
+- [User Cohorts](user_cohorts.md): Display the monthly cohorts of new users and their activities over time. **(CORE)**

doc/user/admin_area/analytics/instance_statistics.md

@@ -4,7 +4,7 @@ group: Value Stream Management
 info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
 ---
 
-# Instance Statistics
+# Instance Statistics **(CORE)**
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/235754) in GitLab 13.4.
 

doc/user/admin_area/analytics/user_cohorts.md

@@ -4,7 +4,7 @@ group: unassigned
 info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
 ---
 
-# Cohorts
+# Cohorts **(CORE)**
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/23361) in GitLab 9.1.