Merge branch 'docs-ssot-ci-2' into 'master'

Docs: ssot ci/*/files

See merge request gitlab-org/gitlab-ce!28802

doc/ci/interactive_web_terminal/index.md

+---
+type: reference
+---
+
 # Interactive Web Terminals
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/50144) in GitLab 11.3.

doc/ci/large_repositories/index.md

+---
+type: reference
+---
+
 # Optimizing GitLab for large repositories
 
 Large repositories consisting of more than 50k files in a worktree

doc/ci/merge_request_pipelines/index.md

+---
+type: reference
+---
+
 # Pipelines for merge requests
 
 NOTE: **Note**:

doc/ci/quick_start/README.md

+---
+type: reference
+---
+
 # Getting started with GitLab CI/CD
 
 >**Note:** Starting from version 8.0, GitLab [Continuous Integration][ci] (CI)
@@ -35,11 +39,11 @@ project's **Pipelines** page.
 
 ---
 
-This guide assumes that you:
+This guide assumes that you have:
 
-- have a working GitLab instance of version 8.0+r or are using
-  [GitLab.com](https://gitlab.com)
-- have a project in GitLab that you would like to use CI for
+- A working GitLab instance of version 8.0+r or are using
+  [GitLab.com](https://gitlab.com).
+- A project in GitLab that you would like to use CI for.
 
 Let's break it down to pieces and work on solving the GitLab CI puzzle.
 

doc/ci/review_apps/index.md

+---
+type: reference
+---
+
 # Review Apps
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab-ce/issues/21971) in GitLab 8.12. Further additions were made in GitLab 8.13 and 8.14.
 > - Inspired by [Heroku's Review Apps](https://devcenter.heroku.com/articles/github-integration-review-apps), which itself was inspired by [Fourchette](https://github.com/rainforestapp/fourchette).
 
-Review Apps are a collaboration tool that takes the hard work out of providing an environment to showcase product changes.
+Review Apps is a collaboration tool that takes the hard work out of providing an environment to showcase product changes.
 
 ## Introduction
 
@@ -18,7 +22,7 @@ Review Apps:
 
 In the above example:
 
-- A Review App is built every time a commit is pushed to`topic branch`.
+- A Review App is built every time a commit is pushed to `topic branch`.
 - The reviewer fails two reviews before passing the third review.
 - Once the review as passed, `topic branch` is merged into `master` where it's deploy to staging.
 - After been approved in staging, the changes that were merged into `master` are deployed in to production.

doc/ci/runners/README.md

+---
+type: reference
+---
+
 # Configuring GitLab Runners
 
 In GitLab CI, Runners run the code defined in [`.gitlab-ci.yml`](../yaml/README.md).

doc/ci/ssh_keys/README.md

 ---
 last_updated: 2017-12-13
+type: tutorial
 ---
 
 # Using SSH keys with GitLab CI/CD

doc/ci/triggers/README.md

+---
+type: tutorial
+---
+
 # Triggering pipelines through the API
 
 > **Notes**: