rudimentary type docs. Closes #148

Author: Basarat Ali Syed

SUMMARY.md

@@ -36,6 +36,7 @@
 * [Browser QuickStart](docs/quick/browser.md)
 * [TypeScript's Type System](docs/types/type-system.md)
   * [JS Migration Guide](docs/types/migrating.md)
+  * [@types](docs/types/@types.md)
   * [Ambient Declarations](docs/types/ambient/intro.md)
     * [Declaration Files](docs/types/ambient/d.ts.md)
     * [Variables](docs/types/ambient/variables.md)

docs/types/@types.md

@@ -0,0 +1,46 @@
+# `@types`
+
+[Definitely Typed](https://github.com/DefinitelyTyped/DefinitelyTyped) is definitely one of TypeScript's greatest strengths. The community has effectively gone ahead and **documented** the nature of nearly 90% of the top JavaScript projects out there.
+
+This means that you can use these projects in a very interactive an exploratory manner, no need to have the docs open in a seperate window and making sure you don't make a typo.
+
+## Using `@types`
+
+Installation is fairly simple as it just works on top of `npm`. So as an example you can install type definitions for `jquery` simply as :
+
+```
+npm install @types/jquery --save-dev
+```
+
+`@types` supports both *global* and *module* type definitions.
+
+
+### Global `@types`
+
+After installation, to use a type definition globally you simply add it to your tsconfig.json e.g. to use jquery
+
+```
+{
+    "compilerOptions": {
+        "types": [
+            "jquery"
+        ]
+    }
+}
+```
+
+Now you should be able to use `$` or `jQuery` *globally* in your project.
+
+> Alternatively, if you don't include it in tsconfig.json, you can use it only in particular files simply by adding `/// <reference types="jquery" />` to the top of that file. (I personally don't do this).
+
+For *libraries* I generally recommend using *modules*:
+
+### Module `@types`
+
+After installation, no special configuration required really. You just use it like a module e.g.
+
+```
+import * as $ from "jquery";
+
+// Use $ at will in this module :)
+```