Add docs for Group Activity Analytics API

doc/api/api_resources.md

@@ -120,6 +120,7 @@ The following API resources are available outside of project and group contexts
 | [Events](events.md)                                | `/events`, `/users/:id/events` (also available for projects)            |
 | [Feature flags](features.md)                       | `/features`                                                             |
 | [Geo Nodes](geo_nodes.md) **(PREMIUM ONLY)**       | `/geo_nodes`                                                            |
+| [Group Activity Analytics](group_activity_analytics.md) **(STARTER)**  | `/analytics/group_activity/{issues_count | merge_requests_count}`  |
 | [Import repository from GitHub](import.md)         | `/import/github`                                                        |
 | [Issues](issues.md)                                | `/issues` (also available for groups and projects)                      |
 | [Issues Statistics](issues_statistics.md)          | `/issues_statistics` (also available for groups and projects)           |

doc/api/group_activity_analytics.md

+# Group Activity Analytics API
+
+> **Note:** This feature was [introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/26460) in GitLab 12.9.
+
+## Get count of recently created issues for group
+
+```plaintext
+GET /analytics/group_activity/issues_count
+```
+
+Parameters:
+
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+| `group_path` | string | yes | Group path |
+
+Example request:
+
+```shell
+curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/analytics/group_activity/issues_count?group_path=gitlab-org
+```
+
+Example response:
+
+```json
+[
+  { issues_count : 10 }
+]
+```
+
+## Get count of recently created merge requests for group
+
+```plaintext
+GET /analytics/group_activity/merge_requests_count
+```
+
+Parameters:
+
+| Attribute | Type | Required | Description |
+| --------- | ---- | -------- | ----------- |
+| `group_path` | string | yes | Group path |
+
+Example request:
+
+```shell
+curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/analytics/group_activity/merge_requests_count?group_path=gitlab-org
+```
+
+Example response:
+
+```json
+[
+  { merge_requests_count : 10 }
+]
+```