added typescript typings to the project

Author: YashdalfTheGray

index.d.ts

@@ -0,0 +1,18 @@
+// Type definitions for docker-file-parser 1.0
+
+export interface CommandEntry {
+    name: string;
+    args: string[];
+    lineno: number;
+    raw: string;
+    error?: string;
+}
+
+export interface ParseOptions {
+    includeComments: boolean;
+}
+
+export function parse(
+    contents: string,
+    options?: ParseOptions
+): CommandEntry[];

package.json

@@ -22,6 +22,7 @@
     }
   ],
   "main": "index.js",
+  "types": "index.d.ts",
   "scripts": {
     "test": "set -e; for t in test/test_*.js; do node $t; done"
   },