chore: update docs [skip ci]

README.md

@@ -4,8 +4,64 @@
 base library for oclif CLIs
 
 [![Version](https://img.shields.io/npm/v/@oclif/core.svg)](https://npmjs.org/package/@oclif/core)
-[![CircleCI](https://circleci.com/gh/oclif/core/tree/master.svg?style=svg)](https://circleci.com/gh/oclif/core/tree/master)
+[![CircleCI](https://circleci.com/gh/oclif/core/tree/main.svg?style=svg)](https://circleci.com/gh/oclif/core/tree/main)
 [![Downloads/week](https://img.shields.io/npm/dw/@oclif/core.svg)](https://npmjs.org/package/@oclif/core)
-[![License](https://img.shields.io/npm/l/@oclif/core.svg)](https://github.com/oclif/core/blob/master/package.json)
+[![License](https://img.shields.io/npm/l/@oclif/core.svg)](https://github.com/oclif/core/blob/main/package.json)
 
-Docs coming soon...
+
+Usage
+=====
+
+Without the generator, you can create a simple CLI like this:
+
+**TypeScript**
+```js
+#!/usr/bin/env ts-node
+
+import * as fs from 'fs'
+import {Command, flags} from '@oclif/core'
+
+class LS extends Command {
+  static flags = {
+    version: flags.version(),
+    help: flags.help(),
+    // run with --dir= or -d=
+    dir: flags.string({
+      char: 'd',
+      default: process.cwd(),
+    }),
+  }
+
+  async run() {
+    const {flags} = this.parse(LS)
+    let files = fs.readdirSync(flags.dir)
+    for (let f of files) {
+      this.log(f)
+    }
+  }
+}
+
+LS.run()
+.catch(require('@oclif/errors/handle'))
+```
+
+Then run either of these with:
+
+```sh-session
+$ ./myscript
+...files in current dir...
+$ ./myscript --dir foobar
+...files in ./foobar...
+$ ./myscript --version
+myscript/0.0.0 darwin-x64 node-v9.5.0
+$ ./myscript --help
+USAGE
+  $ @oclif/core
+
+OPTIONS
+  -d, --dir=dir  [default: /Users/jdickey/src/github.com/oclif/core]
+  --help         show CLI help
+  --version      show CLI version
+```
+
+See the [generator](https://github.com/oclif/oclif) for all the options you can pass to the command.