fix(cli): support help command (#1355)

cli/src/help.ts

@@ -0,0 +1,13 @@
+import { Command } from 'clipanion'
+
+/**
+ * A command that prints the usage of all commands.
+ *
+ * Paths: `-h`, `--help`
+ */
+export class HelpCommand extends Command<any> {
+  static paths = [[`-h`], [`--help`]]
+  async execute() {
+    await this.context.stdout.write(this.cli.usage())
+  }
+}

cli/src/index.ts

@@ -7,6 +7,7 @@ import { version } from '../package.json'
 import { ArtifactsCommand } from './artifacts'
 import { BuildCommand } from './build'
 import { CreateNpmDirCommand } from './create-npm-dir'
+import { HelpCommand } from './help'
 import { NewProjectCommand } from './new'
 import { PrePublishCommand } from './pre-publish'
 import { RenameCommand } from './rename'
@@ -24,6 +25,7 @@ cli.register(PrePublishCommand)
 cli.register(VersionCommand)
 cli.register(NewProjectCommand)
 cli.register(RenameCommand)
+cli.register(HelpCommand)
 
 cli
   .run(process.argv.slice(2), {