Update WordPress documentation (5.7)

Author: simon04

assets/javascripts/templates/pages/about_tmpl.coffee

@@ -863,7 +863,7 @@ credits = [
     'https://github.com/pallets/werkzeug/blob/master/LICENSE.rst'
   ], [
     'Wordpress',
-    '2003-2020 WordPress Foundation',
+    '2003-2021 WordPress Foundation',
     'GPLv2+',
     'https://wordpress.org/about/license/'
   ], [

lib/docs/scrapers/wordpress.rb

@@ -2,7 +2,7 @@ module Docs
   class Wordpress < UrlScraper
     self.name = 'WordPress'
     self.type = 'wordpress'
-    self.release = '5.6'
+    self.release = '5.7'
     self.base_url = 'https://developer.wordpress.org/reference/'
     self.initial_paths = %w(
       functions/
@@ -32,7 +32,7 @@ class Wordpress < UrlScraper
     ]
 
     options[:attribution] = <<-HTML
-      &copy; 2003&ndash;2020 WordPress Foundation<br>
+      &copy; 2003&ndash;2021 WordPress Foundation<br>
       Licensed under the GNU GPLv2+ License.
     HTML