Added convenience make targets and refined documentation in the HelloPlayDate example target.

Examples/HelloPlaydate/Makefile

@@ -28,4 +28,23 @@ OBJS += build/Modules/playdate_device.o
 build/game_simulator.o: Sources/HelloPlaydate/*.swift build/Modules/playdate_simulator.o
 	$(SWIFT_EXEC) $(SWIFT_FLAGS) $(SWIFT_FLAGS_SIMULATOR) -c $(filter %.swift,$^) -o $@
 $(OBJDIR)/pdex.${DYLIB_EXT}: build/game_simulator.o
-SIMCOMPILER += build/game_simulator.o
+SIMCOMPILER += build/game_simulator.o
+
+# MARK: - Convenience Targets
+# The SDK's common.mk (included via swift.mk) already provides the build
+# targets, all packaging $(PRODUCT) with pdc:
+#   make             device binary + simulator dylib (alias: all)
+#   make simulator   simulator dylib only
+#   make device      device binary only
+.PHONY: run clean-swiftpm
+
+# Build the simulator flavor and launch the pdx in the Playdate Simulator.
+run: simulator
+	open -a "$(SDK)/bin/Playdate Simulator.app" $(PRODUCT)
+
+# common.mk's clean removes the build folder, $(PRODUCT), and the binaries
+# copied into Source/; also drop the .build folder SwiftPM leaves behind
+# when building with build.sh.
+clean: clean-swiftpm
+clean-swiftpm:
+	-rm -rf .build