feat: Add disable_nojekyll and cname options (#119)

* feat: Add disable_nojekyll and cname options
* docs: Add cname and disable_nojekyll
* chore: Add vim
* chore(release): 3.3.0-0
* ci: Add codecov/codecov-action
* refactor: Enhance warning message

- Add .nojekyll file by default to only the master and gh-pages branches. When the file already exists, this action does nothing.
- When we set other branches to publish_branch, this action does not add .nojekyll file.

cf. https://github.com/peaceiris/actions-gh-pages/issues/112#issuecomment-589678269

Close #112

Co-authored-by: Daniel Himmelstein <daniel.himmelstein@gmail.com>
Co-authored-by: Nicolas Vanhoren <nicolas.vanhoren@gmail.com>

README.md

@@ -72,6 +72,8 @@ Three tokens are supported.
 - [Options](#options)
   - [⭐️ `personal_token`](#%EF%B8%8F-personal_token)
   - [⭐️ `github_token`](#%EF%B8%8F-github_token)
+  - [⭐️ CNAME](#%EF%B8%8F-cname)
+  - [⭐️ Disable `.nojekyll`](#%EF%B8%8F-disable-nojekyll)
   - [⭐️ Allow empty commits](#%EF%B8%8F-allow-empty-commits)
   - [⭐️ Keeping existing files](#%EF%B8%8F-keeping-existing-files)
   - [⭐️ Deploy to external repository](#%EF%B8%8F-deploy-to-external-repository)
@@ -246,6 +248,36 @@ jobs:
 + github_token: ${{ secrets.GITHUB_TOKEN }}
 ```
 
+### ⭐️ CNAME
+
+To add `CNAME` file, we can set the `cname` option.
+
+For more details about `CNAME`, read the official documentation: [Managing a custom domain for your GitHub Pages site - GitHub Help](https://help.github.com/en/github/working-with-github-pages/managing-a-custom-domain-for-your-github-pages-site)
+
+```yaml
+- name: Deploy
+  uses: peaceiris/actions-gh-pages@v3
+  with:
+    deploy_key: ${{ secrets.ACTIONS_DEPLOY_KEY }}
+    publish_dir: ./public
+    cname: github.com
+```
+
+### ⭐️ Disable `.nojekyll`
+
+By default, this action adds the `.nojekyll` file to only the `master` and `gh-pages` branches. When the file already exists, this action does nothing.
+
+To disable this behavior, we can set the `disable_nojekyll` option to `true`.
+
+```yaml
+- name: Deploy
+  uses: peaceiris/actions-gh-pages@v3
+  with:
+    deploy_key: ${{ secrets.ACTIONS_DEPLOY_KEY }}
+    publish_dir: ./public
+    disable_nojekyll: true
+```
+
 ### ⭐️ Allow empty commits
 
 By default, a commit will not be generated when no file changes. If you want to allow an empty commit, set the optional parameter `allow_empty_commit` to `true`.