fix(docker): Push to dockerhub by github actions

Dockerhub build became premium feature that we can't use for free.
So we change to use Github Actions to build the docker images and
push to Dockerhub.

Signed-off-by: Yibai Zhang <xm1994@gmail.com>

.github/workflows/dockerhub.yml

@@ -0,0 +1,25 @@
+name: Update dockerhub
+
+on:
+  push:
+    branches:
+      - 'master'
+      - 'ci-docker'
+
+jobs:
+  docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v2
+      - name: Login to DockerHub
+        uses: docker/login-action@v1 
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          tags: ctfwiki/ctf-wiki:latest

README-zh_CN.md

@@ -59,13 +59,8 @@ python3 scripts/docs.py serve
 
 如果你只是想本地浏览，并不想修改文档？试试 Docker 把！
 
-> 注意：在 DockerHub 上的 `ctfwiki/ctf-wiki` 为过时版本，您可使用以下命令手动构建。
-
 ```
-# docker run -d --name=ctf-wiki -p 4100:80 ctfwiki/ctf-wiki
-git clone https://github.com/ctf-wiki/ctf-wiki.git
-docker build -t ctf-wiki .
-docker run --name ctf-wiki -d -p 4100:80 ctf-wiki
+docker run -d --name=ctf-wiki -p 4100:80 ctfwiki/ctf-wiki
 ```
 随后即可在浏览器中访问 [http://localhost:4100/](http://localhost:4100/) 阅读 CTF Wiki 。
 

README.md

@@ -58,13 +58,8 @@ python3 scripts/docs.py serve
 
 If you just want to view it statically, try Docker!
 
-> Note: The `ctfwiki/ctf-wiki` on DockerHub is out of date, but you can manually build it using the following command
-
 ```
-# docker run -d --name=ctf-wiki -p 4100:80 ctfwiki/ctf-wiki
-git clone https://github.com/ctf-wiki/ctf-wiki.git
-docker build -t ctf-wiki .
-docker run --name ctf-wiki -d -p 4100:80 ctf-wiki
+docker run -d --name=ctf-wiki -p 4100:80 ctfwiki/ctf-wiki
 ```
 And then access [http://localhost:4100/](http://localhost:4100/) .