[ruby/json] Few doc tweaks:

- Also modified the gemspec files' blob as the ragel's `parser.rl`
  file was removed in https://github.com/ruby/json/commit/c8d5236a921e

https://github.com/ruby/json/commit/b2b106e314

ext/json/json.gemspec

@@ -52,7 +52,7 @@ spec = Gem::Specification.new do |s|
     s.files += Dir["lib/json/ext/**/*.jar"]
   else
     s.extensions = Dir["ext/json/**/extconf.rb"]
-    s.files += Dir["ext/json/**/*.{c,h,rl}"]
+    s.files += Dir["ext/json/**/*.{c,h}"]
   end
 end
 

ext/json/lib/json/common.rb

@@ -172,10 +172,10 @@ module JSON
   #   JSON.generate({ count: 3, items: fragments })
   #
   # This allows to easily assemble multiple JSON fragments that have
-  # been peristed somewhere without having to parse them nor resorting
+  # been persisted somewhere without having to parse them nor resorting
   # to string interpolation.
   #
-  # Note: no validation is performed on the provided string. it is the
+  # Note: no validation is performed on the provided string. It is the
   # responsability of the caller to ensure the string contains valid JSON.
   Fragment = Struct.new(:json) do
     def initialize(json)