Add docs for multi-project pipelines graphs

doc/ci/pipelines.md

@@ -186,6 +186,20 @@ by name. The order of severity is:
 
 ![Pipeline mini graph sorting](img/pipelines_mini_graph_sorting.png)
 
+### Multi-project pipelines graphs
+
+> [Introduced][ee-2121] in [GitLab Enterprise Edition Premium][eep] 9.3.
+
+When projects are connected via [triggers], those connections are displayed in
+the pipeline graph by showing inbound and outbound connections for upstream and
+downstream pipeline dependencies.
+
+![Multi-projects pipelines graphs](img/multi_project_pipelines_graph.png)
+
+This is useful for larger projects, especially those adopting a micro-services
+architecture, that often have a set of interdependent components which form the
+complete product.
+
 ## How the pipeline duration is calculated
 
 Total running time for a given pipeline would exclude retries and pending
@@ -229,9 +243,11 @@ respective link in the [Pipelines settings] page.
 [stages]: yaml/README.md#stages
 [runners]: runners/README.html
 [pipelines settings]: ../user/project/pipelines/settings.md
-[triggers]: triggers/README.md
+[triggers]: triggers/README.md#ci-job-token
 [ce-5742]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5742
 [ce-6242]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6242
 [ce-7931]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7931
 [ce-9760]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9760
 [regexp]: https://gitlab.com/gitlab-org/gitlab-ce/blob/2f3dc314f42dbd79813e6251792853bc231e69dd/app/models/commit_status.rb#L99
+[eep]: https://about.gitlab.com/gitlab-ee/ "GitLab Enterprise Edition Premium"
+[ee-2121]: https://gitlab.com/gitlab-org/gitlab-ee/issues/2121

doc/ci/triggers/README.md

@@ -26,7 +26,7 @@ which is used to authenticate with the [GitLab Container Registry][registry].
 
 This way of triggering can only be used when invoked inside `.gitlab-ci.yml`,
 and it creates a dependent pipeline relation visible on the
-[pipeline graph](../pipelines.md#pipelines-graphs). For example:
+[pipeline graph](../pipelines.md#multi-project-pipelines-graphs). For example:
 
 ```yaml
 build_docs: