Improve CI docs (#555)

* Improve CI docs

* More dos

* More docs

* Link

building/config.json

@@ -661,6 +661,12 @@
     "path": "building/tracks/stories/tuples.santas-helper.md",
     "title": "Santa's Helper"
   },
+  {
+    "uuid": "b99fb54b-a9ce-4a50-bca4-6a928cc77ec6",
+    "slug": "tracks/ci/workflows",
+    "path": "building/tracks/ci/workflows.md",
+    "title": "Workflows"
+  },
   {
     "uuid": "191b0fa1-96e2-48a6-ad2e-c34f57443799",
     "slug": "tracks/ci/migrating-from-travis",

building/tracks/ci/README.md

@@ -2,3 +2,8 @@
 
 At Exercism, we use [GitHub Actions](https://github.com/features/actions) to handle our [continuous integration](https://en.wikipedia.org/wiki/Continuous_integration) (CI) and [continuous deployment](https://en.wikipedia.org/wiki/Continuous_deployment) (CD) needs.
 This includes running tests, formatting things, and deploying things.
+
+For more information, check:
+
+- [Workflows](/docs/building/tracks/ci/workflows)
+- [Setting up CI for new tracks](/docs/building/tracks/new/setup-continuous-integration)

building/tracks/ci/workflows.md

@@ -0,0 +1,41 @@
+# Workflows
+
+GitHub Actions uses the concept of _workflows_, which are scripts that run automatically whenever a specific event occurs (e.g. pushing a commit).
+
+Each GitHub Actions workflow is defined in a `.yml` file in the `.github/workflows` directory.
+For information on workflows, check the following docs:
+
+- [Workflow syntax](https://docs.github.com/en/actions/writing-workflows/workflow-syntax-for-github-actions)
+- [Choosing when your workflow runs](https://docs.github.com/en/actions/writing-workflows/choosing-when-your-workflow-runs/triggering-a-workflow)
+- [Choosing where your workflow runs](https://docs.github.com/en/actions/writing-workflows/choosing-where-your-workflow-runs)
+- [Choose what your workflow does](https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does)
+- [Writing workflows](https://docs.github.com/en/actions/writing-workflows)
+- [Best practices](/docs/building/github/gha-best-practices)
+
+## Shared workflows
+
+Some workflows are shared across repositories.
+These workflows _should not be changed_.
+
+### General workflows
+
+- `sync-labels.yml`: automatically syncs the repository's labels from a `labels.yml` file
+
+### Track-specific workflows
+
+- `configlet.yml`: runs the [configlet tool](/docs/building/configlet), which checks if a track's (configuration) files are properly structured - both syntactically and semantically
+- `no-important-files-changed.yml`: checks if pull requests would cause all existing solutions of one or more changes exercises to be re-run
+- `test.yml`: verify the track's exercises
+
+### Tooling-specific workflows
+
+- `deploy.yml`: deploy the tooling Docker image to Docker Hub and ECR
+
+## Custom workflows
+
+Maintainers are free to add custom workflows to their repos.
+Examples of such workflows could be:
+
+- Linting of shell scripts ([example](https://github.com/exercism/configlet/blob/3baa09608c8ac327315c887608c13a68ae8ac359/.github/workflows/shellcheck.yml))
+- Auto-commenting on pull requests ([example](https://github.com/exercism/elixir/blob/b737f80cc93fcfdec6c53acb7361819834782470/.github/workflows/pr-comment.yml))
+- Etc.