README.md in bundled_gems-0.2.0 vs README.md in bundled_gems-1.0.0

@@ -1,19 +1,25 @@
 # BundledGems
 
 [![Gem Version](https://badge.fury.io/rb/bundled_gems.svg)](https://badge.fury.io/rb/bundled_gems)
 [![Actions Status](https://github.com/toshimaru/bundled_gems/workflows/Ruby%20Test/badge.svg)](https://github.com/toshimaru/bundled_gems/actions)
 
-Install gem specified in `Gemfile.lock` without `bundle install`.
+Install a gem specified in `Gemfile.lock` without running `bundle install`.
 
+## Motivation
+
+After the emergence of Docker, libraries (such as rubygems) are installed inside Docker or Docker Volume, but we sometimes want to install specific version of libraries in Host machine.
+
+Here comes the bundled_gems command (`bgem`). `bgem` reads your `Gemfile.lock` and install the specific version of the gem.
+
 ## Installation
 
 ```console
 $ gem install bundled_gems
 ```
 
-Then, you can use `bgem` command.
+Then, `bgem` command is available.
 
 ## Usage
 
 ```console
 $ bgem                    
@@ -63,6 +69,6 @@
 
 The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
 
 ## Code of Conduct
 
-Everyone interacting in the BundledGem project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/toshimaru/bundled_gems/blob/master/CODE_OF_CONDUCT.md).
+Everyone interacting in the BundledGem project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/toshimaru/bundled_gems/blob/main/CODE_OF_CONDUCT.md).