[meta] add auto-changelog

.npmrc

@@ -1 +1,3 @@
 package-lock=false
+allow-same-version=true
+message=v%s

CHANGELOG.md

@@ -0,0 +1,8 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+Generated by [`auto-changelog`](https://github.com/CookPete/auto-changelog).

package.json

@@ -8,7 +8,9 @@
 		"pretest": "npm run lint",
 		"tests-only": "node test",
 		"test": "npm run tests-only",
-		"posttest": "npx aud"
+		"posttest": "npx aud",
+		"version": "auto-changelog && git add CHANGELOG.md",
+		"postversion": "auto-changelog && git add CHANGELOG.md && git commit --no-edit --amend && git tag -f \"v$(node -e \"console.log(require('./package.json').version)\")\""
 	},
 	"repository": {
 		"type": "git",
@@ -32,11 +34,19 @@
 	"homepage": "https://github.com/ljharb/side-channel#readme",
 	"devDependencies": {
 		"@ljharb/eslint-config": "^15.0.2",
+		"auto-changelog": "^1.16.2",
 		"eslint": "^6.7.2",
 		"tape": "^4.11.0"
 	},
 	"dependencies": {
 		"es-abstract": "^1.16.2",
 		"object-inspect": "^1.7.0"
+	},
+	"auto-changelog": {
+		"output": "CHANGELOG.md",
+		"template": "keepachangelog",
+		"unreleased": false,
+		"commitLimit": false,
+		"backfillLimit": false
 	}
 }