Document instructions to copy database from Android

README.md

@@ -28,6 +28,26 @@ enter the URL to this Git project.
 * Has [phone constraints](https://developer.puri.sm/Librem5/Apps/Guides/Design/Constraints.html) in mind
 * Strictly separates API wrapper from GTK stuff, making former a solid base for other (commandline) clients
 
+## FAQ
+
+### How can I add contacts?
+
+Adding contacts isn't yet supported. Instead, you have to copy
+the database and keys from a Briar Android installation. The most
+convenient way to do so is by using
+[_adb_](https://developer.android.com/studio/command-line/adb).
+Note that your smartphone needs to be rooted for this.
+
+1. Start _briar-gtk_ and register a dummy account. This will create
+the needed directory structure at _~/.briar/_. Close the program afterwards.
+2. Enable _adb_ on your smartphone and give it root permissions.
+3. Connect via _adb_ and gain root permissions using `adb root`.
+4. Copy all important files using `adb pull`:
+_/data/data/org.briarproject.briar.android/app_db/db.mv.db_,
+_/data/data/org.briarproject.briar.android/app_key/db.key_,
+_/data/data/org.briarproject.briar.android/app_key/db.key.bak_
+5. Replace the respecting files in _~/.briar/db_ and _~/.briar/key_.
+
 ## License
 
 This program is free software: you can redistribute it and/or modify