Upgrading github-markup, README fixes

README.md

@@ -22,7 +22,7 @@ Squib::Deck.new do
 end
 ```
 
-That script just created a deck of with 1 image at 825x1125 with the string "Hello, World" in the upper-left corner.
+We just created a deck with 1 card, 825x1125 pixels, with the string "Hello, World" in the upper-left corner, saved to a PNG.
 
 ## Installation
 

squib.gemspec

@@ -39,7 +39,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency "rspec-mocks", "~> 3.0"
   spec.add_development_dependency "redcarpet", '~> 3.1.2'
-  spec.add_development_dependency "github-markup", '~> 1.2.1'
+  spec.add_development_dependency "github-markup", '~> 1.3'
   spec.add_development_dependency "yard"
   spec.add_development_dependency "coveralls"