Normalize Markdown documentation

.github/workflows/main.yml

@@ -13,6 +13,11 @@ jobs:
     steps:
       - uses: actions/checkout@v7
 
+      - name: Lint Markdown
+        uses: DavidAnson/markdownlint-cli2-action@v23
+        with:
+          globs: "**/*.md"
+
       - name: Check formatting
         run: make format-check
 

.markdownlint.json

@@ -0,0 +1,8 @@
+{
+  "MD013": {
+    "line_length": 100
+  },
+  "MD024": {
+    "siblings_only": true
+  }
+}

README.md

@@ -1,4 +1,4 @@
-# Tennis C++ Kata
+# Tennis kata in C++
 
 [![CI](https://github.com/Coding-Cuddles/tennis-cpp-kata/actions/workflows/main.yml/badge.svg)](https://github.com/Coding-Cuddles/tennis-cpp-kata/actions/workflows/main.yml)
 [![C++17](https://img.shields.io/badge/C%2B%2B-17-blue.svg)](https://en.cppreference.com/w/cpp/17)
@@ -110,6 +110,26 @@ and run the setup commands again.
 Setup is complete when the build succeeds and CTest discovers the disabled
 test.
 
+## Work on the kata
+
+1. Remove the `DISABLED_` prefix from the test in `test_tennis.cpp`, then
+   implement the scoring behavior in `tennis.h`.
+
+2. Run the tests after each change. Use Make when it is installed:
+
+   ```console
+   make test
+   ```
+
+   Otherwise, use CMake and CTest directly:
+
+   ```console
+   cmake --build build --config Debug
+   ctest --test-dir build --build-config Debug --output-on-failure
+   ```
+
+   Continue when CTest reports `100% tests passed`.
+
 ## Make command reference
 
 Make is optional. Run `make` or `make help` to list these commands in the