Add markdown lint

.markdownlint-cli2.jsonc

@@ -0,0 +1,12 @@
+{
+  "globs": [
+    "*.md",
+    ".github/**/*.md"
+  ],
+
+  // ToDo: Following rules can't be fixed automatically. They should be enabled when fixed.
+  "config": {
+    "MD013": false, // https://github.com/markdownlint/markdownlint/blob/main/docs/RULES.md#md013---line-length
+    "MD033": false // https://github.com/markdownlint/markdownlint/blob/main/docs/RULES.md#md033---inline-html
+  }
+}