Add codeblock and codespan examples

examples/codeblock.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+require_relative "../lib/tty-markdown"
+
+template = <<~MSG
+
+## Codeblock
+
+```ruby
+class Greeter
+  def initialize(name)
+    @name = name
+  end
+
+  def greet
+    puts "Hello \#{@name}"
+  end
+end
+```
+
+MSG
+
+print TTY::Markdown.parse template

examples/codespan.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require_relative "../lib/tty-markdown"
+
+template = <<~MSG
+
+## Codespan
+
+Code like this `foo = []` in line
+
+Another code ```bar = {}``` in line
+
+MSG
+
+print TTY::Markdown.parse template