Write description [skip ci]

README.md

@@ -2,7 +2,7 @@
 
 [![Build Status](https://travis-ci.org/hidakatsuya/prawn-emoji.svg)](https://travis-ci.org/hidakatsuya/prawn-emoji)
 
-Provides support for Emoji in [Prawn](https://github.com/prawnpdf/prawn).
+Prawn::Emoji is an extention for [Prawn](https://github.com/prawnpdf/prawn), provides feature for drawing Emoji.
 
 ## Installation
 

prawn-emoji.gemspec

@@ -10,6 +10,7 @@ Gem::Specification.new do |spec|
   spec.email         = ['[email protected]']
 
   spec.summary       = 'Provides support for Emoji in Prawn'
+  spec.description   = 'Prawn::Emoji is an extention for Prawn, provides feature for drawing Emoji.'
   spec.homepage      = 'https://github.com/hidakatsuya/prawn-emoji'
   spec.license       = 'MIT'
   spec.platform      = Gem::Platform::RUBY