add publish target

Makefile

@@ -1,3 +1,5 @@
+VERSION = $(shell grep 'const version' cmd/commands/version/version.go | sed -E 's/.*"(.+)"$$/v\1/')
+
 .PHONY: all test clean build install
 
 GOFLAGS ?= $(GOFLAGS:)
@@ -18,3 +20,10 @@ bench: install
 
 clean:
 	go clean $(GOFLAGS) -i ./...
+
+publish:
+	mkdir -p bin/$(VERSION)
+	cd bin/$(VERSION)
+	xgo -v -x --targets="windows/*,darwin/*,linux/386,linux/amd64,linux/arm-5,linux/arm64" -out bee_$(VERSION) github.com/beego/bee
+	cd ..
+	ghr -u beego -r bee $(VERSION) $(VERSION)