Remove reference to github api, add documentation for chart-releaser cli (#77)

* remove reference to github api, add documentation for chart-releaser cli

Signed-off-by: Moritz Schmitz von Hülst <moritz@hauptstadtoffice.com>

README.md

@@ -13,13 +13,17 @@ A GitHub action to turn a GitHub project into a self-hosted Helm chart repo, usi
 
 ### Inputs
 
-For more information on inputs, see the [API Documentation](https://developer.github.com/v3/repos/releases/#input)
-
 - `version`: The chart-releaser version to use (default: v1.2.1)
-- `config`: Optional config file for chart-releaser
+- `config`: Optional config file for chart-releaser. For more information on the config file, see the [documentation](https://github.com/helm/chart-releaser#config-file)
 - `charts_dir`: The charts directory
 - `charts_repo_url`: The GitHub Pages URL to the charts repo (default: `https://<owner>.github.io/<project>`)
 
+### Environment variables
+
+- `CR_TOKEN` (required): The GitHub token of this repository (`${{ secrets.GITHUB_TOKEN }}`)
+
+For more information on environment variables, see the [documentation](https://github.com/helm/chart-releaser#environment-variables).
+
 ### Example Workflow
 
 Create a workflow (eg: `.github/workflows/release.yml`):
@@ -60,6 +64,28 @@ jobs:
 This uses [@helm/chart-releaser-action](https://www.github.com/helm/chart-releaser-action) to turn your GitHub project into a self-hosted Helm chart repo.
 It does this – during every push to `main` – by checking each chart in your project, and whenever there's a new chart version, creates a corresponding [GitHub release](https://help.github.com/en/github/administering-a-repository/about-releases) named for the chart version, adds Helm chart artifacts to the release, and creates or updates an `index.yaml` file with metadata about those releases, which is then hosted on GitHub Pages
 
+#### Example using custom config
+
+`workflow.yml`:
+```yaml
+- name: Run chart-releaser
+  uses: helm/chart-releaser-action@v1.2.0
+  with:
+    charts_dir: charts
+    config: cr.yaml
+    charts_repo_url: xxxxxx
+  env:
+    CR_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
+```
+
+`cr.yaml`:
+```yaml
+owner: myaccount
+git-base-url: https://api.github.com/
+```
+
+For options see [config-file](https://github.com/helm/chart-releaser#config-file). 
+
 ## Code of conduct
 
 Participation in the Helm community is governed by the [Code of Conduct](CODE_OF_CONDUCT.md).