Merge branch 'jl-add-component-subheadings-docs' into 'master'

Add subheadings to components page

See merge request gitlab-org/gitlab-ce!28382

doc/development/architecture.md

@@ -212,6 +212,8 @@ To serve repositories over SSH there's an add-on application called gitlab-shell
 
 ### Components
 
+#### Component Diagram
+
 ```mermaid
 graph TB
 
@@ -280,15 +282,15 @@ graph TB
 
 ```
 
----
-
-**Legend**:
+#### Component Legend
 
 * ✅ - Automatically configured
 * ⚙ - Requires additional configuration
 * ⤓ - Additional software/service required
 * ❌ - Not available
 
+#### Component Table
+
 | Component | Description | [Omnibus GitLab](https://docs.gitlab.com/omnibus/README.html) | [GitLab chart](https://docs.gitlab.com/charts/) | [Minikube Minimal](https://docs.gitlab.com/charts/development/minikube/#deploying-gitlab-with-minimal-settings) | [GitLab.com](https://gitlab.com) | CE/EE |
 | --------- | ----------- |:--------------------:|:------------------:|:-----:|:--------:|:--------:|
 | NGINX | Routes requests to appropriate components, terminates SSL | [✅](https://docs.gitlab.com/omnibus/settings/nginx.html) | [✅](https://docs.gitlab.com/charts/charts/nginx/index.html) | [⚙](https://docs.gitlab.com/charts/charts/nginx/index.html) | [✅](https://about.gitlab.com/handbook/engineering/infrastructure/production-architecture/#service-architecture) | CE & EE |
@@ -326,6 +328,8 @@ graph TB
 | Jaeger: deployed apps | Distributed tracing for deployed apps | [⤓](https://docs.gitlab.com/ee/user/project/operations/tracing.html) | [⤓](https://docs.gitlab.com/ee/user/project/operations/tracing.html) | [⤓](https://docs.gitlab.com/ee/user/project/operations/tracing.html) | [⤓](https://docs.gitlab.com/ee/user/project/operations/tracing.html) | EE Only |
 | Kubernetes cluster apps | Deploy [Helm](https://docs.helm.sh/), [Ingress](https://kubernetes.io/docs/concepts/services-networking/ingress/), [Cert-Manager](https://docs.cert-manager.io/en/latest/), [Prometheus](https://prometheus.io/docs/introduction/overview/), a [Runner](https://docs.gitlab.com/runner/), [JupyterHub](http://jupyter.org/), [Knative](https://cloud.google.com/knative) to a cluster | [✅](https://docs.gitlab.com/ee/user/project/clusters/#installing-applications) | [✅](https://docs.gitlab.com/ee/user/project/clusters/#installing-applications) | [✅](https://docs.gitlab.com/ee/user/project/clusters/#installing-applications) | [✅](https://docs.gitlab.com/ee/user/project/clusters/#installing-applications) | CE & EE |
 
+#### Component Overview
+
 A typical install of GitLab will be on GNU/Linux. It uses Nginx or Apache as a web front end to proxypass the Unicorn web server. By default, communication between Unicorn and the front end is via a Unix domain socket but forwarding requests via TCP is also supported. The web front end accesses `/home/git/gitlab/public` bypassing the Unicorn server to serve static pages, uploads (e.g. avatar images or attachments), and precompiled assets. GitLab serves web pages and a [GitLab API](https://gitlab.com/gitlab-org/gitlab-ce/tree/master/doc/api) using the Unicorn web server. It uses Sidekiq as a job queue which, in turn, uses redis as a non-persistent database backend for job information, meta data, and incoming jobs.
 
 We also support deploying GitLab on Kubernetes using our [gitlab Helm chart](https://docs.gitlab.com/charts/).