Docs: Add TypeScript example (#155)

* Docs: Add TypeScript example

* WIP: Add tsconfig.json for type-aware linting

It works on the first block but not the second. See diff for additional
context. Any ideas?

* Docs: Remove tsconfig.json and add type-aware rule note

.github/workflows/ci.yml

@@ -44,5 +44,10 @@ jobs:
       run: npm install
       env:
         CI: true
+    - name: Install examples/typescript Packages
+      working-directory: ./examples/typescript
+      run: npm install
+      env:
+        CI: true
     - name: Test
       run: npm run test-cov

examples/typescript/.eslintrc.js

@@ -0,0 +1,22 @@
+"use strict";
+
+module.exports = {
+    root: true,
+    extends: [
+        "eslint:recommended",
+        "plugin:markdown/recommended",
+    ],
+    overrides: [
+        {
+            files: [".eslintrc.js"],
+            env: {
+                node: true
+            }
+        },
+        {
+            files: ["*.ts"],
+            parser: "@typescript-eslint/parser",
+            extends: ["plugin:@typescript-eslint/recommended"]
+        },
+    ]
+};

examples/typescript/.npmrc

@@ -0,0 +1 @@
+package-lock = false

examples/typescript/README.md

@@ -0,0 +1,25 @@
+# React Example
+
+The `@typescript-eslint` parser and the `recommended` config's rules will work in `ts` code blocks. However, [type-aware rules](https://github.com/typescript-eslint/typescript-eslint/blob/master/docs/getting-started/linting/TYPED_LINTING.md) will not work because the code blocks are not part of a compilable `tsconfig.json` project.
+
+```ts
+function hello(name: String) {
+    console.log(`Hello, ${name}!`);
+}
+
+hello(42 as any);
+```
+
+```sh
+$ git clone https://github.com/eslint/eslint-plugin-markdown.git
+$ cd eslint-plugin-markdown/examples/typescript
+$ npm install
+$ npm test
+
+eslint-plugin-markdown/examples/typescript/README.md
+   6:22  error    Don’t use `String` as a type. Use string instead  @typescript-eslint/ban-types
+  10:13  warning  Unexpected any. Specify a different type          @typescript-eslint/no-explicit-any
+
+✖ 2 problems (1 error, 1 warning)
+  1 error and 0 warnings potentially fixable with the `--fix` option.
+```

examples/typescript/package.json

@@ -0,0 +1,13 @@
+{
+  "private": true,
+  "scripts": {
+    "test": "eslint ."
+  },
+  "devDependencies": {
+    "@typescript-eslint/eslint-plugin": "^3.6.1",
+    "@typescript-eslint/parser": "^3.6.1",
+    "eslint": "^7.5.0",
+    "eslint-plugin-markdown": "file:../..",
+    "typescript": "^3.9.7"
+  }
+}