Add markdown formatting check

Author: lucic71

.github/workflows/format.yml

@@ -37,3 +37,6 @@ jobs:
 
       - name: Check format
         run: git diff --exit-code
+
+      - name: Check markdown formatting
+        run: npx prettier@3.6.2 --check "docs/src/**/*.md"

.prettierrc

@@ -0,0 +1,4 @@
+{
+  "proseWrap": "always",
+  "printWidth": 80
+}