add file open

Assets/3rd/DocumentHandler/package.json

@@ -0,0 +1,12 @@
+{
+    "name": "com.drstc.documenthandler",
+    "displayName": "DocumentHandler",
+    "version": "0.1.0",
+    "unity": "2019.4",
+    "description": "Open a document (e.g. .pfd) with a corresponding native app.",
+    "author": {
+        "name": "Draudastic",
+        "email": "via gitHub",
+        "url": "https://github.com/Draudastic26"
+    }
+}