Update readme 📘

- adding `store#remove` example

Author: vladimyr

readme.md

@@ -34,6 +34,11 @@ fs.createReadStream('/tmp/somefile.txt')
 store.createReadStream({ key: 'somefile.txt' })
   .pipe(fs.createWriteStream('/tmp/somefile.txt'));
 
+// remove
+store.remove({ key: 'somefile.txt' }, function (err) {
+   // ...
+});
+
 // exists
 store.exists({ key: 'somefile.txt' }, function (err, exists) {
   // ...