Add node modules and compiled JavaScript from main

node_modules/is-docker/index.d.ts

@@ -0,0 +1,15 @@
+/**
+Check if the process is running inside a Docker container.
+
+@example
+```
+import isDocker = require('is-docker');
+
+if (isDocker()) {
+	console.log('Running inside a Docker container');
+}
+```
+*/
+declare function isDocker(): boolean;
+
+export = isDocker;