Merge remote-tracking branch 'origin/master' into mkirk/ri-2-19-4

BUILDING.md

@@ -70,10 +70,18 @@ Open the `Signal.xcworkspace` in Xcode.
 open Signal.xcworkspace
 ```
 
-In the Signal target on the General tab, change the Team drop down to
-your own. You will need an Apple Developer account for that. On the
-Capabilities tab turn off Push Notifications and Data Protection. Only
-Background Modes should remain on.
+In the TARGETS area of the General tab, change the Team drop down to
+your own. You will need to do that for all the listed targets, for ex. 
+Signal, SignalShareExtension, and SignalMessaging. You will need an Apple
+Developer account for this. 
+
+On the Capabilities tab, turn off Push Notifications and Data Protection,
+while keeping Background Modes on. The App Groups capability will need to
+remain on in order to access the shared data storage. The App ID needs to
+match the SignalApplicationGroup string set in TSConstants.h. 
+
+If you wish to test the Documents API, the iCloud capability will need to
+be on with the iCloud Documents option selected.
 
 Build and Run and you are ready to go!