Update Rust documentation (1.15.0)

assets/javascripts/templates/pages/about_tmpl.coffee

@@ -511,7 +511,7 @@ credits = [
     'https://raw.githubusercontent.com/rails/rails/master/activerecord/MIT-LICENSE'
   ], [
     'Rust',
-    '2016 The Rust Project Developers',
+    '2010 The Rust Project Developers',
     'MIT',
     'https://raw.githubusercontent.com/rust-lang/rust/master/LICENSE-MIT'
   ], [

lib/docs/scrapers/rust.rb

@@ -1,7 +1,7 @@
 module Docs
   class Rust < UrlScraper
     self.type = 'rust'
-    self.release = '1.14.0'
+    self.release = '1.15.0'
     self.base_url = 'https://doc.rust-lang.org/'
     self.root_path = 'book/index.html'
     self.initial_paths = %w(
@@ -31,7 +31,7 @@ module Docs
     end
 
     options[:attribution] = <<-HTML
-      &copy; 2016 The Rust Project Developers<br>
+      &copy; 2010 The Rust Project Developers<br>
       Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
     HTML