Feat: Makefile adds target dependencies

Makefile

@@ -11,22 +11,31 @@ ${BIN}: ${SRC}
 test:
 	go test -modfile=go_test.mod -v -short -cover ./...
 
-api:
+api: .go/bin/godoc2md
 	@sed '/^## API$$/,$$d' -i README.md
 	@echo '## API' >> README.md
-	@godoc2md github.com/studio-b12/gowebdav | sed '/^$$/N;/^\n$$/D' |\
+	@$< github.com/studio-b12/gowebdav | sed '/^$$/N;/^\n$$/D' |\
 	sed '2d' |\
 	sed 's/\/src\/github.com\/studio-b12\/gowebdav\//https:\/\/github.com\/studio-b12\/gowebdav\/blob\/master\//g' |\
 	sed 's/\/src\/target\//https:\/\/github.com\/studio-b12\/gowebdav\/blob\/master\//g' |\
 	sed 's/^#/##/g' >> README.md
 
-check:
+check: .go/bin/gocyclo
 	gofmt -w -s $(SRC)
 	@echo
-	gocyclo -over 15 .
+	.go/bin/gocyclo -over 15 .
 	@echo
 	go vet -modfile=go_test.mod ./...
 
+
+.go/bin/godoc2md:
+	@mkdir -p $(@D)
+	@GOPATH="$(CURDIR)/.go" go install github.com/davecheney/godoc2md@latest
+
+.go/bin/gocyclo:
+	@mkdir -p $(@D)
+	@GOPATH="$(CURDIR)/.go" go install github.com/fzipp/gocyclo/cmd/gocyclo@latest
+
 clean:
 	@rm -f ${BIN}