add description of bug in README

Author: blackpuppy

README.md

@@ -1,6 +1,6 @@
 # vue2-datepicker-demo
 
-> A Vue.js project
+> A vue2-datepicker demo to reproduce a bug.
 
 ## Build Setup
 
@@ -19,3 +19,30 @@ npm run build --report
 ```
 
 For detailed explanation on how things work, checkout the [guide](http://vuejs-templates.github.io/webpack/) and [docs for vue-loader](http://vuejs.github.io/vue-loader).
+
+## How to reproduce
+
+``` bash
+# create an empty Vue project
+vue init webpack vue2-datepicker-demo
+
+# install dependencies
+cd vue2-datepicker-demo/
+npm install
+
+# add vue2-datepicker
+npm install vue2-datepicker --save
+
+# serve with hot reload at localhost:8080
+npm run dev
+```
+
+Error in the output:
+
+```
+...
+ error  in ./~/vue2-datepicker/src/datepicker/index.vue
+
+Module build failed: Error: Couldn't find preset "latest" relative to directory ".../node_modules/vue2-datepicker"
+...
+```