(#89) Update description to match pub.dev requirements

Author: lakscastro

pubspec.yaml

@@ -1,5 +1,5 @@
 name: shared_storage
-description: "Flutter plugin to work with external storage."
+description: "Flutter plugin to work with external storage with privacy-friendly APIs."
 version: 0.4.2
 homepage: https://github.com/lakscastro/shared-storage
 repository: https://github.com/lakscastro/shared-storage