Add a config input parameter to append to hyde.yml configuration

[emmadesilva]

You can also specify configuration options using the config input. The lines in this input will be appended to the hyde.yml file in the root directory, allowing you to configure many parts of the Hyde project before the build. Fixes #24

- name: Build and Deploy HydePHP Site
  uses: hydephp/action@master
    with:
      deploy-to: "pages"
      config: |
        name: Example
        url: ${{ github.deployment.url }}