chore: Use Go cache for helm-docs installation (#44)

Signed-off-by: Sergiy Kulanov <[email protected]>

Makefile

@@ -177,13 +177,13 @@ controller-gen: ## Download controller-gen locally if necessary.
 PROJECT_DIR := $(shell dirname $(abspath $(lastword $(MAKEFILE_LIST))))
 define go-get-tool
 @[ -f $(1) ] || { \
-set -e ;\
+set -ex ;\
 TMP_DIR=$$(mktemp -d) ;\
 cd $$TMP_DIR ;\
 go mod init tmp ;\
 echo "Downloading $(2)" ;\
-go get -d $(2)@$(3) ;\
-GOBIN=$(PROJECT_DIR)/bin go install $(2) ;\
+GOCACHE=$$GOCACHE GOMODCACHE=$$GOMODCACHE go get -d $(2)@$(3) ;\
+GOBIN=$(PROJECT_DIR)/bin GOCACHE=$$GOCACHE GOMODCACHE=$$GOMODCACHE go install $(2) ;\
 rm -rf $$TMP_DIR ;\
 }
 endef