chore(docs): add CI docs

Author: dirkdev98

docs/.vitepress/config.js

@@ -275,6 +275,10 @@ function getHomeSidebar() {
             },
           ],
         },
+        {
+          text: "Continuous Integration",
+          link: "/docs/continuous-integration.html",
+        },
       ],
     },
 

docs/docs/continuous-integration.md

@@ -0,0 +1,46 @@
+# Continuous Integration (CI)
+
+Running various checks in CI can be handled by Compas as well.
+
+::: code-group
+
+```shell [GitHub]
+compas init github
+# Overwrites `.github/workflows/check.yml`
+```
+
+:::
+
+The supported templates checkout the repository, configure cache when applicable
+and then start Compas via `compas ci`. If the CI provider that you want to use
+is not listed, try to mimic the following Shell commands:
+
+```shell
+# Either install packages via the package manager that you use and invoke Compas
+npm ci
+npx compas ci
+
+# OR let Compas infer the used package manager and install packages for you.
+
+# Retrieve the used Compas version from the package.json (e.g 0.8.0 or latest).
+COMPAS_VERSION=$(jq --raw-output '.devDependencies.compas // .dependencies.compas // "latest" | ltrimstr("v")' package.json)
+npx compas@$COMPAS_VERSION ci
+```
+
+## Steps
+
+- **Package manager**: Compas starts with the package installation command of
+  the inferred package manager.
+- **Docker**: Required Docker containers are started, when specified in the
+  configs.
+- **Migrations**: If migrations are enabled, they will be executed.
+- **Format and linting**: Supported linters like Prettier and ESLint are
+  executed
+- **Tests**: If a test command is inferred or found in the config, it is
+  executed.
+
+## Multiple repositories
+
+The default CI templates provided by Compas only checkout the current
+repository. If things like tests require multiple checked out repositories to
+get a complete workspace, please edit the templates manually.