make: better comments

Makefile

@@ -1,24 +1,22 @@
 CC = gcc
 SRC_DIR = src
 INC_DIR = include
-# This is where the targets will be compiled from
-TARGET_DIR = examples
 TEST_DIR = test
-CFLAGS = -g -I$(INC_DIR) -Wall
+CFLAGS = -O3 -I$(INC_DIR) -Wall
 LDFLAGS = -lm
 TEST_SRC = $(wildcard $(TEST_DIR)/*.c)
 
 ifeq ($(MAKECMDGOALS), test)
 	# If `test` is passed as a cmd argument, extend flags to handle unit tests 
-	TARGET_SRC = $(wildcard $(TEST_DIR)/*.c)
+	TARGET_SRC = $(TEST_SRC)
 	TARGETS = $(patsubst $(TEST_DIR)/%.c,%,$(TEST_SRC))
 	TARGET_DIR = test
 else
+	TARGET_SRC = $(wildcard $(TARGET_DIR)/*.c)
+	TARGET_DIR = examples
 	# Strip file path so each demo source gets a target,
 	# e.g. examples/01_demo.c -> 01_demo
-	TARGET_SRC = $(wildcard $(TARGET_DIR)/*.c)
 	TARGETS = $(patsubst $(TARGET_DIR)/%.c, %, $(TARGET_SRC))
-	TARGET_DIR = examples
 endif
 
 # What to do by default (no arguments)
@@ -36,4 +34,3 @@ $(TARGETS): %: $(TARGET_DIR)/%.o $(wildcard $(SRC_DIR)/*.o)
 RM = rm -rf
 clean:
 	$(RM) $(TARGETS) $(SRC_DIR)/*.o $(TARGET_DIR)/*.o tests
-