[Docs] Fix build phase for RN 0.46+

Author: ovr

docs/manual-setup.rst

@@ -24,6 +24,12 @@ To this::
 
     export NODE_BINARY=node
     export SENTRY_PROPERTIES=sentry.properties
+    
+    # If you are using RN 0.46+
+    ../node_modules/sentry-cli-binary/bin/sentry-cli react-native xcode \
+      ../node_modules/react-native/scripts/react-native-xcode.sh
+      
+    # For RN < 0.46
     ../node_modules/sentry-cli-binary/bin/sentry-cli react-native xcode \
       ../node_modules/react-native/packager/react-native-xcode.sh