Add type definitions

types/index.d.ts

@@ -0,0 +1,21 @@
+import Vue, { PluginObject } from "vue";
+
+declare const VueJSModal: PluginObject<VueJSModalOptions>;
+export default VueJSModal;
+
+export declare interface VueJSModalOptions {
+  componentName?: string;
+  dialog?: boolean;
+}
+
+declare interface VModal {
+  show(name: string, params?: object): void;
+  hide(name: string, params?: object): void;
+  toggle(name: string, params?: object): void;
+}
+
+declare module "vue/types/vue" {
+  interface Vue {
+    $modal: VModal;
+  }
+}