Add MAINTAINING.md and deploy action script

.github/workflows/create-yorkie-app-publish.yml

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+name: create-yorkie-app-publish
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+    paths:
+      - tools/create-yorkie-app/**
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout 🛎️
+        uses: actions/checkout@v2
+      - name: Setup Node 🔧
+        uses: actions/setup-node@v2
+        with:
+          node-version: '18'
+          cache: 'npm'
+          cache-dependency-path: package-lock.json
+          registry-url: 'https://registry.npmjs.org'
+      - run: npm install
+      - run: cd tools/create-yorkie-app && npm run build
+      - run: npm publish --provenance
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}

tools/create-yorkie-app/MAINTAINING.md

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+# Maintaining create-yorkie-app
+
+This package is an automated tool to scaffold an example project that shows practical usage of yorkie-js-sdk.
+
+```bash
+.
+├── MAINTAINING.md
+├── README.md
+├── frameworks.ts   # abstract data object representing examples/ directory
+├── index.ts        # main script
+├── package.json
+├── tsconfig.json
+└── webpack.config.js
+```
+
+## Adding a New Example
+
+Add information about your new example in [frameworks.ts](https://github.com/yorkie-team/yorkie-js-sdk/blob/main/tools/create-yorkie-app/frameworks.ts).
+
+Choose or create an appropriate category (e.g. vanilla, react, nextjs, vue, ...) and add an object like below to variants array.
+
+```ts
+{
+  name: directory_name,
+  display: displayed_name_in_prompt
+}
+```
+
+## Publishing a New Version
+
+Update the version in [package.json](https://github.com/yorkie-team/yorkie-js-sdk/blob/main/tools/create-yorkie-app/package.json#L3).
+
+Publication will be done via [create-yorkie-app-publish.yml](https://github.com/yorkie-team/yorkie-js-sdk/blob/main/.github/workflows/create-yorkie-app-publish.yml) when changes are pushed into main branch.