Feature/centos (#176)

* check on CentOS container

* update README

* update links

* update CHANGELOG

* refactor insertLf()

.github/workflows/verify-on-container.yml

@@ -1,101 +0,0 @@
-# https://help.github.com/en/articles/workflow-syntax-for-github-actions
-
-name: Docker container
-
-on:
-- push
-
-jobs:
-  ssh-pem:
-    name: Connect to github.com (PEM format)
-    runs-on: ${{ matrix.os }}
-    container: ${{ matrix.container }}
-    strategy:
-      matrix:
-        os:
-        - ubuntu-16.04
-        - ubuntu-18.04
-        - ubuntu-20.04
-        container:
-        - ubuntu:16.04
-        - ubuntu:18.04
-        - ubuntu:20.04
-      fail-fast: false
-    steps:
-    - name: Install packages
-      run: |
-        apt update
-        apt -y install openssh-client git
-    - name: Checkout source codes
-      uses: actions/checkout@v2
-    - name: Install SSH key
-      uses: ./.
-      with:
-        key: ${{ secrets.SSH_KEY_PEM }}
-        known_hosts: ${{ secrets.KNOWN_HOSTS }}
-    - name: print created files
-      run: ls -l /root/.ssh
-    - name: git clone through SSH
-      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
-  ssh-pkcs8:
-    name: Connect to github.com (PKCS8 format)
-    runs-on: ${{ matrix.os }}
-    container: ${{ matrix.container }}
-    strategy:
-      matrix:
-        os:
-        - ubuntu-16.04
-        - ubuntu-18.04
-        - ubuntu-20.04
-        container:
-        - ubuntu:16.04
-        - ubuntu:18.04
-        - ubuntu:20.04
-      fail-fast: false
-    steps:
-    - name: Install packages
-      run: |
-        apt update
-        apt -y install openssh-client git
-    - name: Checkout source codes
-      uses: actions/checkout@v2
-    - name: Install SSH key
-      uses: ./.
-      with:
-        key: ${{ secrets.SSH_KEY_PKCS8 }}
-        known_hosts: ${{ secrets.KNOWN_HOSTS }}
-    - name: print created files
-      run: ls -l /root/.ssh
-    - name: git clone through SSH
-      run: git clone git@github.com:shimataro/ssh-key-action.git tmp
-  ssh-rfc4716:
-    name: Connect to github.com (RFC4716 format)
-    runs-on: ${{ matrix.os }}
-    container: ${{ matrix.container }}
-    strategy:
-      matrix:
-        os:
-        - ubuntu-16.04
-        - ubuntu-18.04
-        - ubuntu-20.04
-        container:
-        - ubuntu:16.04
-        - ubuntu:18.04
-        - ubuntu:20.04
-      fail-fast: false
-    steps:
-    - name: Install packages
-      run: |
-        apt update
-        apt -y install openssh-client git
-    - name: Checkout source codes
-      uses: actions/checkout@v2
-    - name: Install SSH key
-      uses: ./.
-      with:
-        key: ${{ secrets.SSH_KEY_RFC4716 }}
-        known_hosts: ${{ secrets.KNOWN_HOSTS }}
-    - name: print created files
-      run: ls -l /root/.ssh
-    - name: git clone through SSH
-      run: git clone git@github.com:shimataro/ssh-key-action.git tmp