👷 add languagetool

.github/workflows/lint.yml

@@ -0,0 +1,17 @@
+name: reviewdog
+
+on: [pull_request]
+
+jobs:
+  linting:
+
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Check style and grammar
+        uses: reviewdog/action-languagetool@v1
+        with:
+          github_token: ${{ secrets.github_token }}
+          patterns: '**/*.md **/*.tex'
+          language: de-DE
+          level: warning