Remove superfluous typings in examples.

examples/console/src/typings.d.ts

@@ -1,4 +1 @@
 /// <reference path="../../../typings/codemirror/codemirror.d.ts"/>
-
-// For a Thenable reference in jupyter-js-services
-type Thenable<T> = Promise<T>

examples/filebrowser/src/typings.d.ts

@@ -1,4 +1 @@
 /// <reference path="../../../typings/codemirror/codemirror.d.ts"/>
-
-// For a Thenable reference in jupyter-js-services
-type Thenable<T> = Promise<T>

examples/notebook/src/typings.d.ts

@@ -1,4 +1 @@
 /// <reference path="../../../typings/codemirror/codemirror.d.ts"/>
-
-// For a Thenable reference in jupyter-js-services
-type Thenable<T> = Promise<T>

examples/terminal/src/typings.d.ts

@@ -1,4 +1 @@
 /// <reference path="../../../typings/codemirror/codemirror.d.ts"/>
-
-// For a Thenable reference in jupyter-js-services
-type Thenable<T> = Promise<T>