feat(docdown): new type definition (#46020)

Definition types for 'docdown':
- definitioins files
- tests

https://github.com/jdalton/docdown#readme

Thanks!

types/docdown/docdown-tests.ts

@@ -0,0 +1,18 @@
+import docdown = require('docdown');
+import { Options } from 'docdown';
+
+const options: Options = {
+    path: './some/path',
+    url: 'https://github.com/username/project/blob/master/my.js',
+};
+const markdown = docdown(options);
+// $ExpectType string
+docdown({
+    path: './some/path',
+    url: 'https://example.com/my.js',
+    lang: 'js',
+    sort: false,
+    style: 'github',
+    title: 'README',
+    toc: 'properties',
+});

types/docdown/index.d.ts

@@ -0,0 +1,50 @@
+// Type definitions for docdown 0.7
+// Project: https://github.com/jdalton/docdown#readme
+// Definitions by: Piotr Błażejewicz <https://github.com/peterblazejewicz>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+/**
+ * A simple JSDoc to Markdown documentation generator.
+ * Generates Markdown documentation based on JSDoc comments.
+ */
+declare function docdown(options: docdown.Options): string;
+
+declare namespace docdown {
+    interface Options {
+        /**
+         * the input file pat
+         */
+        path: string;
+        /**
+         * The source URL.
+         */
+        url: string;
+        /**
+         *  The language indicator for code blocks.
+         * @default 'js'
+         */
+        lang?: string;
+        /**
+         * Specify whether entries are sorted.
+         * @default true
+         */
+        sort?: boolean;
+        /**
+         * The hash style for links ('default' or 'github').
+         * @default 'default'
+         */
+        style?: string;
+        /**
+         * The documentation title.
+         * @default '<%= basename(options.path) %> API documentation'
+         */
+        title?: string;
+        /**
+         * The table of contents organization style ('categories' or 'properties').
+         * @default 'properties'
+         */
+        toc?: string;
+    }
+}
+
+export = docdown;

types/docdown/tsconfig.json

@@ -0,0 +1,23 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictFunctionTypes": true,
+        "strictNullChecks": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "docdown-tests.ts"
+    ]
+}

types/docdown/tslint.json

@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }