Update gemspec to include License, Changelog and Readme

semian.gemspec

@@ -1,28 +1,32 @@
-$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 = '[email protected]'
-  s.license = 'MIT'
-
-  s.files = Dir['{lib,ext}/**/**/*.{rb,h,c}']
-  s.extensions = ['ext/semian/extconf.rb']
+  s.homepage = "https://github.com/shopify/semian"
+  s.authors = ["Scott Francis", "Simon Eskildsen", "Dale Hamel"]
+  s.email = "[email protected]"
+  s.license = "MIT"
 
   s.metadata = {
-    'allowed_push_host' => 'https://rubygems.org',
-    'bug_tracker_uri' => 'https://github.com/Shopify/semian/issues',
-    'changelog_uri' => 'https://github.com/Shopify/semian/blob/master/CHANGELOG.md',
-    'source_code_uri' => 'https://github.com/Shopify/semian',
+    "allowed_push_host" => "https://rubygems.org",
+    "bug_tracker_uri" => "https://github.com/Shopify/semian/issues",
+    "changelog_uri" => "https://github.com/Shopify/semian/blob/master/CHANGELOG.md",
+    "source_code_uri" => "https://github.com/Shopify/semian",
   }
+
+  s.files = ::Dir["{lib,ext}/**/**/*.{rb,h,c}"] +
+            ::Dir.glob('*.md')
+
+  s.extensions = ["ext/semian/extconf.rb"]
 end