add Makefile & update README

Makefile

@@ -0,0 +1,26 @@
+.PHONY: clean
+clean:
+	go clean -i ./...
+
+.PHONY: fmt
+fmt:
+	go fmt *.go
+
+.PHONY: vet
+vet:
+	go vet github.com/6543/go-hexcolor
+
+.PHONY: misspell
+misspell:
+	@hash misspell > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
+		GO111MODULE=off $(GO) get -u github.com/client9/misspell/cmd/misspell; \
+	fi
+	misspell -w *
+
+.PHONY: test
+test:
+	go test
+
+.PHONY: vendor
+vendor:
+	GO111MODULE=on; go mod tidy && go mod vendor

README.md

@@ -1,6 +1,8 @@
 # Hex Color Library for Go
 
+## Features:
+ * Normalize/Parse hex color
+ * convert from/to color.RGBA
+
 ## ToDo
-* [ ] Normalize/Parse function
-* [ ] Some Convert func
 * [ ] Predefine standard colors (red, blue, ... based on CSS colors)