README.md in akashiyaki-0.1.0 vs README.md in akashiyaki-0.2.0

@@ -16,11 +16,11 @@
 
 Or install it yourself as:
 
     $ gem install akashiyaki
 
-## Usage
+## Library
 
 ```rb
 require "akashiyaki"
 
 client = Akashiyaki::Client.new(company_id, login_id, password)
@@ -28,13 +28,70 @@
 client.finish_work
 client.start_break
 client.finish_break
 ```
 
+## CLI
+
+Akashiyaki includes `ak4` command that is a CLI tool to access AKASHI.
+
+Basic usage:
+
+```bash
+# To start work
+ak4 work start
+
+# To finish work
+ak4 work finish
+
+# To start break
+ak4 break start
+
+# To finish break
+ak4 break finish
+```
+
+When `ak4` is executed without account information, `ak4` asks you about your account:
+
+```bash
+$ ak4 work finish
+Company ID: mycompany
+Login ID: myid
+Password: %
+```
+
+If you think it's too much bother to enter account information everytime,  you can save your account as configuration file `~/.config/ak4/account.yaml` (or `~/.config/ak4/account.json`):
+
+```yaml
+company: mycompany
+id: myid
+password: mypassword
+```
+
+`ak4` reads account information from `$XDG_CONFIG_HOME` directory.
+
+If you don't want to save your password, you can save only company ID and login ID:
+
+```yaml
+company: mycompany
+id: myid
+```
+
+So `ak4` asks you about only password.
+
+You can also use command options:
+
+```bash
+Options:
+      [--config=CONFIG]
+  -c, [--company=COMPANY]
+  -i, [--id=ID]
+  -p, [--password=PASSWORD]
+```
+
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
-
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
 
 ## Contributing
 
 Bug reports and pull requests are welcome on GitHub at https://github.com/nownabe/akashiyaki.