fix: add description for ngPackage property in package.json

Motivation: IDE support

Author: dherges

integration/samples/secondary/package.json

@@ -1,4 +1,5 @@
 {
+  "$schema": "../../../src/package.schema.json",
   "name": "@sample/secondary-lib",
   "description": "A sample library with configuration in package.json",
   "version": "1.0.0-pre.0",
@@ -9,7 +10,6 @@
     "@angular/common": "^4.1.2"
   },
   "ngPackage": {
-    "$schema": "../../../src/lib/ng-package.schema.json",
     "lib": {
       "entryFile": "public_api.ts"
     }

integration/samples/secondary/sub-module/package.json

@@ -1,4 +1,5 @@
 {
+  "$schema": "../../../../src/package.schema.json",
   "name": "@sample/secondary/sub-module",
   "description": "A sub module library",
   "version": "1.0.0-pre.0",

src/package.schema.json

@@ -4,7 +4,10 @@
     { "$ref": "http://json.schemastore.org/package" },
     {
       "properties": {
-        "ngPackage": { "$ref": "./ng-package.schema.json" }
+        "ngPackage": {
+          "$ref": "./ng-package.schema.json",
+          "description": "Angular Package description"
+        }
       },
       "required": []
     }