Update stores.md

The link to ./src/stores pointed to a 404

website/src/docs/stores.md

@@ -141,4 +141,4 @@ function defaultStore () {
 
 A pattern like this, where users can pass options via a function call if necessary, is recommended.
 
-See the [./src/store](https://github.com/transloadit/uppy/tree/feature/store/src/store) folder in the repository for more inspiration.
+See the [./src/store](https://github.com/transloadit/uppy/tree/master/src/store) folder in the repository for more inspiration.