README.md in flexdot-1.0.2 vs README.md in flexdot-2.0.0

@@ -1,7 +1,8 @@
 # Flexdot
 
+[![Gem Version](https://badge.fury.io/rb/flexdot.svg)](https://badge.fury.io/rb/flexdot)
 [![Test](https://github.com/hidakatsuya/flexdot/workflows/Test/badge.svg?branch=master)](https://github.com/hidakatsuya/flexdot/actions?query=workflow%3ATest)
 
 A Flexible and Rake based dotfile manager.
 
 ## Getting Started
@@ -10,29 +11,52 @@
 
 Ruby 2.5+
 
 ### Installing
 
-Install it as:
+Create the following directory structure:
 
-    $ gem install flexdot
-
-Then, create the following directory structure:
-
 ```
 $HOME/
-  dotfiles/
+├── dotfiles/
+:
 ```
 
-Create a `$HOME/dotfiles/Rakefile` with the following codes:
+Create a `Gemfile` to install Flexdot:
 
+    $ cd $HOME/dotfiles
+    $ bundle init
+
+Add this line to the `Gemfile`:
+
 ```ruby
+gem 'flexdot'
+```
+
+Or install it yourself as:
+
+    $ gem install flexdot
+
+Then, create a `$HOME/dotfiles/Rakefile` with the following codes:
+
+```ruby
 require 'flexdot'
 
-Flexdot.install_tasks(
-  base_dir: '.',                # $HOME/dotfiles/
-  target_dir: '/home/username'  # $HOME/
+Flexdot.setup(
+  home_dir: '/home/username',
+
+  # (optional)
+  # The dotfile directory path.
+  # Default '.'.
+  dotfiles_dir: '.',
+
+  # (optional)
+  # The `rake install` command will be available to install the dotfile for the specified index file.
+  # Default nil.
+  #
+  # Note that the `rake install` command is always available if you have a single index file.
+  default_index: 'name_of_an_index_file'
 )
 ```
 
 Finally, run `rake -T` in the `$HOME/dotfiles` and make sure that the output is as follows:
 
@@ -92,16 +116,28 @@
 ├── macOS.yml
 ├── ubuntu.yml
 └── Rakefile
 ```
 
+### Rakefile
+
+```ruby
+require 'flexdot'
+
+Flexdot.setup(
+  home_dir: '..',
+  default_index: 'macOS'
+)
+```
+
 ### Available Commands
 
 When you run the `rake -T` command in that directory structure, you should have two installation commands available:
 
     $ rake -T
     rake clear_backups   # Clear all backups
+    rake install         # Install dotfiles for macOS
     rake install:macOS   # Install dotfiles for macOS
     rake install:ubuntu  # Install dotfiles for ubuntu
 
 ### Dotfile Index File
 
@@ -174,9 +210,13 @@
     start.sh: .xkeysnail
     stop.sh: .xkeysnail
 ```
 
 ### Installing dotfiles
+
+    $ rake install
+
+Or
 
     $ rake install:macOS
 
 The following is the output result: