add a Dockerfile for local viewing without install

Dockerfile

@@ -0,0 +1,7 @@
+FROM node:20-alpine
+RUN corepack enable
+WORKDIR /app
+COPY . .
+RUN yarn install
+EXPOSE 8080
+CMD ["yarn", "start"]

README.md

@@ -45,9 +45,10 @@ Keep the PR restricted to changes related to the translation.
 ## Development
 
 Files are in the `src` folder. To see it locally:
+- `yarn install` to install dependencies
 - `yarn test` to run the tests
 - `yarn build` to transpile.
-- `yarn start` to serve
+- `yarn start` or `yarn start-docker` to serve. The latter uses a Docker container.
 - Open `http://127.0.0.1:8080/git-cheatsheet.html` to view the page
 
 CI is on [Github Actions](https://github.com/ndp/git-cheatsheet/actions).

package.json

@@ -8,9 +8,12 @@
     "build": "yarn build-js && yarn build-styles",
     "build-js": "webpack --entry ./src/git-cheatsheet.js -o ./git-cheatsheet/ --mode production --target browserslist --devtool source-map",
     "build-styles": "node ./src/build-styles.js",
+    "docker-build": "docker build -t git-cheatsheet .",
+    "docker-run": "docker run -p 8080:8080 git-cheatsheet",
     "clean": "rm -f git-cheatsheet/*.map git-cheatsheet/*.js ./git-cheatsheet/styles.css",
     "test": "jasmine spec/*_spec.mjs",
-    "start": "npx http-server"
+    "start": "npx http-server",
+    "start-docker": "npm run docker-build && npm run docker-run"
   },
   "repository": {
     "type": "git",