docs: update Error message (#309)

Author: ahoseinian

lib/AsyncStorage.js

@@ -27,7 +27,7 @@ To fix this issue try these steps:
 
   • Rebuild and restart the app.
 
-  • Run the packager with \`--clearCache\` flag.
+  • Run the packager with \`--reset-cache\` flag.
 
   • If you are using CocoaPods on iOS, run \`pod install\` in the \`ios\` directory and then rebuild and re-run the app.