chore: Update Makefile to match conventional standards

Makefile

@@ -1,18 +1,46 @@
 GO?=go
 GOLANGCI_LINT_VERSION=$(shell grep GOLANGCI_LINT_VERSION: .github/workflows/main.yml | awk '{ print $$2 }')
+ifdef VERSION
+	GO_LDFLAGS+=-X main.version=${VERSION}
+endif
+ifdef COMMIT
+	GO_LDFLAGS+=-X main.commit=${COMMIT}
+endif
+ifdef DATE
+	GO_LDFLAGS+=-X main.date=${DATE}
+endif
+ifdef BUILT_BY
+	GO_LDFLAGS+=-X main.builtBy=${BUILT_BY}
+endif
+PREFIX?=/usr/local
 
 .PHONY: default
-default: run build-all test lint format
+default: build
+
+.PHONY: smoketest
+smoketest: run build-all test lint format
+
+.PHONY: build
+build:
+ifeq (${GO_LDFLAGS},)
+	go build . || ( rm -f chezmoi ; false )
+else
+	go build -ldflags "${GO_LDFLAGS}" . || ( rm -f chezmoi ; false )
+endif
 
 .PHONY: install
-install:
+install: build
+	install -m 755 chezmoi "${DESTDIR}${PREFIX}/bin"
+
+.PHONY: install-from-git-working-copy
+install-from-git-working-copy:
 	go install -ldflags "-X main.version=$(shell git describe --abbrev=0 --tags) \
 		-X main.commit=$(shell git rev-parse HEAD) \
 		-X main.date=$(shell git show -s --format=%ct HEAD) \
 		-X main.builtBy=source"
 
-.PHONY: build
-build:
+.PHONY: build-in-git-working-copy
+build-in-git-working-copy:
 	go build -ldflags "-X main.version=$(shell git describe --abbrev=0 --tags) \
 		-X main.commit=$(shell git rev-parse HEAD) \
 		-X main.date=$(shell git show -s --format=%ct HEAD) \

docs/CONTRIBUTING.md

@@ -6,6 +6,7 @@
 * [Generated code](#generated-code)
 * [Contributing changes](#contributing-changes)
 * [Managing releases](#managing-releases)
+* [Building and installing with `make`](#building-and-installing-with-make)
 * [Packaging](#packaging)
 * [Updating the website](#updating-the-website)
 
@@ -26,12 +27,7 @@ chezmoi's source code.
 
 chezmoi requires Go 1.16 or later.
 
-chezmoi is a standard Go project, using standard Go tooling, with a few extra
-tools. Ensure that these extra tools are installed with:
-
-```console
-$ make ensure-tools
-```
+chezmoi is a standard Go project, using standard Go tooling.
 
 Build chezmoi:
 
@@ -56,6 +52,12 @@ Run chezmoi:
 $ go run .
 ```
 
+Run a set of smoketests, including cross-compilation, tests, and linting:
+
+```console
+$ make smoketest
+```
+
 ---
 
 ## Generated code
@@ -167,6 +169,28 @@ $ brew bump-formula-pr --tag=v1.2.3 chezmoi
 
 ---
 
+## Building and installing with `make`
+
+chezmoi can be built with GNU make, assuming you have the Go toolchain
+installed.
+
+Running `make` will build a `chezmoi` binary in the current directory for the
+host OS and architecture. To embed version information in the binary and control
+installation the following variables are available:
+
+| Variable    | Example                | Purpose                                         |
+| ----------- | ---------------------- | ----------------------------------------------- |
+| `$VERSION`  | `v2.0.0`               | Set version.                                    |
+| `$COMMIT`   | `3895680a`...          | Set the git commit at which the code was built. |
+| `$DATE`     | `2019-11-23T18:29:25Z` | The time of the build.                          |
+| `$BUILT_BY` | `homebrew`             | The packaging system performing the build.      |
+| `$PREFIX`   | `/usr`                 | Installation prefix.                            |
+| `$DESTDIR`  | `install-root`         | Fake installation root.                         |
+
+Running `make install` will install the `chezmoi` binary in `${DESTDIR}${PREFIX}/bin`.
+
+---
+
 ## Packaging
 
 If you're packaging chezmoi for an operating system or distribution: