ci: 👷 setup markdown linter workflow

Author: maxbarsukov

.github/workflows/markdown.yml

@@ -0,0 +1,32 @@
+name: Markdown CI
+
+on:
+  push:
+    branches:
+      - master
+    paths:
+      - ".github/workflows/*"
+      - ".markdownlint.jsonc"
+      - "**/*.md"
+  pull_request:
+    branches:
+      - master
+    paths:
+      - ".github/workflows/*"
+      - ".markdownlint.jsonc"
+      - "**/*.md"
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: markdownlint-cli
+        uses: nosborn/github-action-markdown-cli@v3.3.0
+        with:
+          files: "*.md"
+          config_file: .markdownlint.jsonc
+          dot: true

.markdownlint.jsonc

@@ -1,4 +1,7 @@
 {
+  // I can set heading levels at my discretion!
+  "MD001": false,
+
   // Style of unordered lists..
   "MD007": {
     "indent": 2,