add Strongbox password manager (#999)

README.md

@@ -916,6 +916,7 @@ Any comments, suggestions? [Let us know!](https://github.com/jaywcjlove/awesome-
 * [LastPass](https://lastpass.com/) - Password management tool for Mac OS and browser.
 * [MacPass](https://macpass.github.io/) - Open-source KeePass Mac OS client. [![Open-Source Software][OSS Icon] ![Freeware][Freeware Icon]](https://github.com/mstarke/MacPass)
 * [SafeInCloud](https://safe-in-cloud.com/en/) - Cross Platform password management, low cost app! [![App Store][app-store Icon]](https://itunes.apple.com/app/safeincloud-password-manager/id883070818)
+* [Strongbox](https://strongboxsafe.com/) - Secure Password Management for iOS and MacOS. Open Source. Compatible with KeePass and Password Safe. [![Open-Source Software][OSS Icon]](https://github.com/strongbox-password-safe/Strongbox) [![App Store][app-store Icon]](https://apps.apple.com/us/app/strongbox/id1270075435?mt=12)
 
 #### Finder Tools