fixed typo

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2017-presen PanJiaChen
+Copyright (c) 2017-present PanJiaChen
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -149,4 +149,4 @@ If you find this project useful, you can buy author a glass of juice :tropical_d
 
 [MIT](https://github.com/PanJiaChen/vue-element-admin/blob/master/LICENSE)
 
-Copyright (c) 2017-presen PanJiaChen
+Copyright (c) 2017-present PanJiaChen

README.zh-CN.md

@@ -162,4 +162,4 @@ Detailed changes for each release are documented in the [release notes](https://
 
 [MIT](https://github.com/PanJiaChen/vue-element-admin/blob/master/LICENSE)
 
-Copyright (c) 2017-presen PanJiaChen
+Copyright (c) 2017-present PanJiaChen