add make install support

Makefile

@@ -20,6 +20,7 @@ REPO_ROOT=$(PWD)
 # autodetect host GOOS and GOARCH by default, even if go is not installed
 GOOS=$(shell hack/util/goos.sh)
 GOARCH=$(shell hack/util/goarch.sh)
+INSTALL_DIR=$(shell hack/util/goinstalldir.sh)
 # use the official module proxy by default
 GOPROXY=https://proxy.golang.org
 # default build image
@@ -31,6 +32,7 @@ CACHE_VOLUME=kind-build-cache
 # variables for consistent logic, don't override these
 CONTAINER_REPO_DIR=/src/kind
 CONTAINER_OUT_DIR=$(CONTAINER_REPO_DIR)/_output/bin
+HOST_OUT_DIR=$(REPO_ROOT)/_output/bin
 
 # standard "make" target -> builds
 all: build
@@ -62,7 +64,11 @@ kind: make-cache
 # alias for building kind
 build: kind
 
+# use: make install INSTALL_DIR=/usr/local/bin
+install: build
+	cp $(HOST_OUT_DIR)/kind $(INSTALL_DIR)/kind
+
 # standard cleanup target
 clean: clean-cache
 
-.PHONY: make-cache clean-cache kind build all clean
+.PHONY: all make-cache clean-cache kind build install clean