Update README and add help target to make

Signed-off-by: Jean-Pierre Huynh <jean-pierre.huynh@ounet.fr>

Makefile

@@ -3,62 +3,61 @@
 #
 all: binary
 
-# remove build artifacts
+
 .PHONY: clean
-clean:
+clean: ## remove build artifacts
 	rm -rf ./build/* cli/winresources/rsrc_* ./man/man[1-9] docs/yaml/gen
 
-# run go test
-# the "-tags daemon" part is temporary
 .PHONY: test
-test:
+test: ## run go test
 	./scripts/test/unit $(shell go list ./... | grep -v '/vendor/')
 
 .PHONY: test-coverage
-test-coverage:
+test-coverage: ## run test coverage
 	./scripts/test/unit-with-coverage $(shell go list ./... | grep -v '/vendor/')
 
 .PHONY: lint
-lint:
+lint: ## run all the lint tools
 	gometalinter --config gometalinter.json ./...
 
 .PHONY: binary
-binary:
+binary: ## build executable for Linux
 	@echo "WARNING: binary creates a Linux executable. Use cross for macOS or Windows."
 	./scripts/build/binary
 
 .PHONY: cross
-cross:
+cross: ## build executable for macOS and Windows
 	./scripts/build/cross
 
 .PHONY: dynbinary
-dynbinary:
+dynbinary: ## build dynamically linked binary
 	./scripts/build/dynbinary
 
 .PHONY: watch
-watch:
+watch: ## monitor file changes and run go test
 	./scripts/test/watch
 
-# Check vendor matches vendor.conf
-vendor: vendor.conf
+vendor: vendor.conf ## check that vendor matches vendor.conf
 	vndr 2> /dev/null
 	scripts/validate/check-git-diff vendor
 
-## generate man pages from go source and markdown
 .PHONY: manpages
-manpages:
+manpages: ## generate man pages from go source and markdown
 	scripts/docs/generate-man.sh
 
-## generate documentation YAML files consumed by docs repo
 .PHONY: yamldocs
-yamldocs:
+yamldocs: ## generate documentation YAML files consumed by docs repo
 	scripts/docs/generate-yaml.sh
 
-## Shellcheck validation
 .PHONY: shellcheck
-shellcheck:
+shellcheck: ## run shellcheck validation
 	scripts/validate/shellcheck
 
+.PHONY: help
+help: ## print this help
+	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z_-]+:.*?## / {sub("\\\\n",sprintf("\n%22c"," "), $$2);printf "\033[36m%-20s\033[0m %s\n", $$1, $$2}' $(MAKEFILE_LIST)
+
+
 cli/compose/schema/bindata.go: cli/compose/schema/data/*.json
 	go generate github.com/docker/cli/cli/compose/schema
 

README.md

@@ -29,6 +29,12 @@ Run all linting:
 $ make -f docker.Makefile lint
 ```
 
+List all the available targets:
+
+```
+$ make help
+```
+
 ### In-container development environment
 
 Start an interactive development environment: