add Clip-Stack by @heruoxin

Author: Joker

categories/tools.md

@@ -2,6 +2,7 @@
 App Name                   | Describe                  | Major Language             | Download 
 :------------------------: | :------------------------ | :------------------------: | :------------------------: 
 [Bitocle for GitHub](https://github.com/mthli/Bitocle) | Bitocle is a simple android app which allows you to view your source code in GitHub.  | Java | [![Get it on Google Play](https://developer.android.com/images/brand/en_app_rgb_wo_45.png)](https://play.google.com/store/apps/details?id=io.github.mthli.Bitocle)  
+[Clip-Stack](https://github.com/heruoxin/Clip-Stack) | An Android clipboard history manager app with Material Design.  | Java | [![Get it on Google Play](https://developer.android.com/images/brand/en_app_rgb_wo_45.png)](https://play.google.com/store/apps/details?id=com.catchingnow.tinyclipboardmanager)  
 [DesignOverlay](https://github.com/Manabu-GT/DesignOverlay-Android) | Android app which displays design image with grid lines to facilitate the tedious design implementation process  | Java | [![Get it on Google Play](https://developer.android.com/images/brand/en_app_rgb_wo_45.png)](https://play.google.com/store/apps/details?id=com.ms_square.android.design.overlay)  
 [Flock](https://github.com/WhisperSystems/Flock) | Private contact and calendar sync for Android. https://whispersystems.org/blog/flock  | Java | [![Get it on Google Play](https://developer.android.com/images/brand/en_app_rgb_wo_45.png)](https://play.google.com/store/apps/details?id=org.anhonesteffort.flock)  
 [OS Monitor](https://github.com/eolwral/OSMonitor) | Android OS Monitor  | Java | [![Get it on Google Play](https://developer.android.com/images/brand/en_app_rgb_wo_45.png)](https://play.google.com/store/apps/details?id=com.eolwral.osmonitor)