Add f-droid reference

Author: marcprux

index.md

@@ -129,6 +129,7 @@ Complaints are especially impactful when they are authored by a citizen of that
 - [Electronic Frontier Foundation](https://www.eff.org/)
 
 ## Other
+- [Install F-Droid](https://f-droid.org) on your Android device(s). The more people that use alternative app marketplaces, the harder it will be to shut them out.
 - Provide feedback directly to Google using their [Android developer verification requirements survey](https://docs.google.com/forms/d/e/1FAIpQLSfN3UQeNspQsZCO2ITkdzMxv81rJDEGGjO-UIDDY28Rz_GEVA/viewform?pli=1).
 - Make your voice heard on social media and with blog posts, and link to https://keepandroidopen.org
 - Combat astroturfing: when you encounter suspect posts on community forums and social media in support of the policy (“Well, actually…”), challenge them and do not be shy.