UPM: explicitly include Runtime/Editor/Samples via files

package.json

@@ -1,16 +1,23 @@
 {
   "name": "com.udexreal.handdriver",
   "displayName": "Hand Driver",
-  "version": "2.1.8",
+  "version": "2.1.9",
   "unity": "2021.3",
   "description": "Hand Driver",
   "author": {
     "name": "Udexreal"
   },
-"dependencies": {
+  "dependencies": {
     "com.unity.nuget.newtonsoft-json": "3.2.1",
-   "com.unity.xr.interaction.toolkit": "2.5.4"
+    "com.unity.xr.interaction.toolkit": "2.5.4"
   },
+  "files": [
+    "Runtime",
+    "Editor",
+    "Samples~",
+    "Documentation~",
+    "README.md"
+  ],
   "samples": [
     {
       "displayName": "Hand Driver Demo",
@@ -18,4 +25,4 @@
       "path": "Samples~/Hand Driver Demo"
     }
   ]
-}
+}