feat(cli): add helpurl flag (#789)

* feat(cli): add helpurl flag

* fix(cli): remove space before helpurl

@commitlint/cli/src/cli.js

@@ -56,6 +56,11 @@ const flags = {
 		type: 'boolean',
 		description: 'display this help message'
 	},
+	'help-url': {
+		alias: 'H',
+		type: 'string',
+		description: 'helpurl in error message'
+	},
 	from: {
 		alias: 'f',
 		default: null,
@@ -220,8 +225,9 @@ async function main(options) {
 	const output = format(report, {
 		color: flags.color,
 		verbose: flags.verbose,
-		helpUrl:
-			'https://github.com/conventional-changelog/commitlint/#what-is-commitlint'
+		helpUrl: flags.helpUrl
+			? flags.helpUrl.trim()
+			: 'https://github.com/conventional-changelog/commitlint/#what-is-commitlint'
 	});
 
 	if (!flags.quiet && output !== '') {

@commitlint/cli/src/cli.test.js

@@ -71,6 +71,20 @@ test('should produce help for problems', async t => {
 	t.is(actual.code, 1);
 });
 
+test('should produce help for problems with correct helpurl', async t => {
+	const cwd = await git.bootstrap('fixtures/default');
+	const actual = await cli(
+		['-H https://github.com/conventional-changelog/commitlint/#testhelpurl'],
+		{cwd}
+	)('foo: bar');
+	t.true(
+		actual.stdout.includes(
+			'Get help: https://github.com/conventional-changelog/commitlint/#testhelpurl'
+		)
+	);
+	t.is(actual.code, 1);
+});
+
 test('should fail for input from stdin without rules', async t => {
 	const cwd = await git.bootstrap('fixtures/empty');
 	const actual = await cli([], {cwd})('foo: bar');