Add a linting CI for formatting and documentation

.github/workflows/linting.yml

@@ -0,0 +1,69 @@
+name: Linting
+
+on:
+  push: ~
+  pull_request: ~
+
+jobs:
+  docs:
+    name: Documentation Kept Updated
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Set up PHP 8.0
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.0'
+          extensions: mbstring
+
+      - name: Get Composer Cache Directory
+        id: composer-cache
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache dependencies
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: ${{ runner.os }}-composer-
+
+      - name: Install dependencies
+        run: composer install
+
+      - name: Generate the documentation
+        run: composer doc
+
+      - name: Check Generated Docs
+        run: git diff --exit-code
+
+  formatting:
+    name: Code Formatting
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Set up PHP 8.0
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.0'
+          extensions: mbstring
+
+      - name: Get Composer Cache Directory
+        id: composer-cache
+        run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+
+      - name: Cache dependencies
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: ${{ runner.os }}-composer-
+
+      - name: Install dependencies
+        run: composer install
+
+      - name: Check formatting
+        run: composer cs-check