📝 Add Install and Usage headers

Author: kozo2

README.md

@@ -14,15 +14,30 @@ https://github.com/jankatins/knitpy
 https://github.com/pystitch/stitch
 
 
+## Install
 
-## Quick Start
+```
+gem install specific_install
+gem specific_install https://github.com/sciruby-jp/rubydown
+```
+
+## Usage
+
+```
+git clone git://github.com/sciruby-jp/rubydown
+cd rubydown/examples
+/usr/local/bundle/bin/rubydown -i rumale.md -e /usr/local/bundle/gems/rubydown-0.1.0/templates/template.html.erb -o rumale-test.html
+```
+
+
+## Quick Start (with Docker)
 
 ```
 docker run -it -v c:/Users:/data ruby bash
 gem install specific_install
 gem specific_install https://github.com/sciruby-jp/rubydown.git
 apt update
 apt install gnuplot
-rubydown -i /usr/local/bundle/gems/rubydown-0.1.0/examples/data_science.md -e /usr/local/bundle/gems/rubydown-0.1.0/templates/template.html.erb -o /data/YOURNAME/data_science.html
+/usr/local/bundle/bin/rubydown -i /usr/local/bundle/gems/rubydown-0.1.0/examples/data_science.md -e /usr/local/bundle/gems/rubydown-0.1.0/templates/template.html.erb -o /data/YOURNAME/data_science.html
 cp data_science.md /data/YOURNAME/data_science.md
 ```