updated typo

Author: Dipak Sarkar

src/index.js

@@ -1,18 +1,18 @@
 import number from './component.vue'
 import vNumber from './directive'
-import Options from './options'
+import options from './options'
 import NumberFormat from './number-format'
 
 export {
   number,
   vNumber,
-  Options,
+  options,
   NumberFormat
 }
 
 function install(Vue, globalOptions) {
   if (globalOptions) {
-    Object.assign(Options, globalOptions)
+    Object.assign(options, globalOptions)
   }
   Vue.directive('number', vNumber)
   Vue.component('number', number)