Update gemspec to include License, Changelog and Readme

semian.gemspec

@@ -1,23 +1,27 @@
-$LOAD_PATH.unshift File.expand_path('../lib', __FILE__)
+# frozen_string_literal: true
 
-require 'semian/version'
-require 'semian/platform'
+$LOAD_PATH.unshift(File.expand_path("../lib", __FILE__))
+
+require "semian/version"
+require "semian/platform"
 
 Gem::Specification.new do |s|
-  s.name = 'semian'
+  s.name = "semian"
   s.version = Semian::VERSION
-  s.summary = 'Bulkheading for Ruby with SysV semaphores'
+  s.summary = "Bulkheading for Ruby with SysV semaphores"
   s.description = <<-DOC
     A Ruby C extention that is used to control access to shared resources
     across process boundaries with SysV semaphores.
   DOC
-  s.homepage = 'https://github.com/shopify/semian'
-  s.authors = ['Scott Francis', 'Simon Eskildsen', 'Dale Hamel']
-  s.email = 'scott.francis@shopify.com'
-  s.license = 'MIT'
+  s.homepage = "https://github.com/shopify/semian"
+  s.authors = ["Scott Francis", "Simon Eskildsen", "Dale Hamel"]
+  s.email = "opensource@shopify.com"
+  s.license = "MIT"
+
+  s.metadata["allowed_push_host"] = "https://rubygems.org"
 
-  s.metadata['allowed_push_host'] = 'https://rubygems.org'
+  s.files = ::Dir["{lib,ext}/**/**/*.{rb,h,c}"] +
+            ::Dir.glob('*.md')
 
-  s.files = Dir['{lib,ext}/**/**/*.{rb,h,c}']
-  s.extensions = ['ext/semian/extconf.rb']
+  s.extensions = ["ext/semian/extconf.rb"]
 end