Update the readme to the intention I want

Author: stoivo

README.md

@@ -1,6 +1,6 @@
 # Ruby CSS Parser [![Build Status](https://github.com/premailer/css_parser/workflows/Run%20css_parser%20CI/badge.svg)](https://github.com/ojab/css_parser/actions?query=workflow%3A%22Run+css_parser+CI%22) [![Gem Version](https://badge.fury.io/rb/css_parser.svg)](https://badge.fury.io/rb/css_parser)
 
-Load, parse and cascade CSS rule sets in Ruby.
+Load, parse and cascade CSS rule sets in Ruby. 
 
 # Setup
 
@@ -10,35 +10,38 @@ gem install css_parser
 
 # Usage
 
+You initiate a document `CssParser::Document.new` and you can start to load it with css. Main methods to add css are: load_uri! (load url and follows @imports based on the full url), load_file! (loads file and follows @imports based on path from file imported) and load_string! (load a block of css). All of these apis tries to absolute all urls
+
+
 ```Ruby
 require 'css_parser'
 include CssParser
 
-parser = CssParser::Parser.new
-parser.load_uri!('http://example.com/styles/style.css')
+document = CssParser::Document.new
+document.load_uri!('http://example.com/styles/style.css')
 
-parser = CssParser::Parser.new
-parser.load_uri!('file://home/user/styles/style.css')
+document = CssParser::Document.new
+document.load_uri!('file://home/user/styles/style.css')
 
 # load a remote file, setting the base_uri and media_types
-parser.load_uri!('../style.css', {base_uri: 'http://example.com/styles/inc/', media_types: [:screen, :handheld]})
+document.load_uri!('../style.css', {base_uri: 'http://example.com/styles/inc/', media_types: [:screen, :handheld]})
 
 # load a local file, setting the base_dir and media_types
-parser.load_file!('print.css', '~/styles/', :print)
+document.load_file!('print.css', '~/styles/', :print)
 
 # load a string
-parser = CssParser::Parser.new
-parser.load_string! 'a { color: hotpink; }'
+document = CssParser::Document.new
+document.load_string! 'a { color: hotpink; }'
 
 # lookup a rule by a selector
-parser.find_by_selector('#content')
+document.find_by_selector('#content')
 #=> 'font-size: 13px; line-height: 1.2;'
 
 # lookup a rule by a selector and media type
-parser.find_by_selector('#content', [:screen, :handheld])
+document.find_by_selector('#content', [:screen, :handheld])
 
 # iterate through selectors by media type
-parser.each_selector(:screen) do |selector, declarations, specificity|
+document.each_selector(:screen) do |selector, declarations, specificity|
   ...
 end
 
@@ -47,24 +50,24 @@ css = <<-EOT
   body { margin: 0 1em; }
 EOT
 
-parser.add_block!(css)
+document.add_block!(css)
 
 # output all CSS rules in a single stylesheet
-parser.to_s
+document.to_s
 => #content { font-size: 13px; line-height: 1.2; }
    body { margin: 0 1em; }
 
 # capturing byte offsets within a file
-parser.load_uri!('../style.css', {base_uri: 'http://example.com/styles/inc/', capture_offsets: true)
-content_rule = parser.find_rule_sets(['#content']).first
+document.load_uri!('../style.css', {base_uri: 'http://example.com/styles/inc/', capture_offsets: true)
+content_rule = document.find_rule_sets(['#content']).first
 content_rule.filename
 #=> 'http://example.com/styles/styles.css'
 content_rule.offset
 #=> 10703..10752
 
 # capturing byte offsets within a string
-parser.load_string!('a { color: hotpink; }', {filename: 'index.html', capture_offsets: true)
-content_rule = parser.find_rule_sets(['a']).first
+document.load_string!('a { color: hotpink; }', {filename: 'index.html', capture_offsets: true)
+content_rule = document.find_rule_sets(['a']).first
 content_rule.filename
 #=> 'index.html'
 content_rule.offset