docs: update author and contributors

Author: mrholek

package.json

@@ -2,7 +2,18 @@
   "name": "@coreui/coreui-free-angular-admin-template",
   "version": "2.0.0-beta.5",
   "description": "CoreUI Free Angular 2+ Admin Template",
-  "author": "Łukasz Holeczek",
+  "author": {
+    "name": "Łukasz Holeczek",
+    "url": "http://holeczek.pl",
+    "github": "https://github.com/mrholek",
+    "twitter": "https://twitter.com/lukaszholeczek"
+  },
+  "contributors": [
+    {
+      "name": "Andrzej Kopański",
+      "url": "https://github.com/xidedix"
+    }
+  ],
   "homepage": "https://coreui.io/angular",
   "copyright": "Copyright 2018 creativeLabs Łukasz Holeczek",
   "license": "MIT",