adds to the API guidelines the proper spelling of Arel

activerecord/lib/active_record/relation/query_methods.rb

@@ -260,8 +260,8 @@ def build_joins(relation, joins)
     def build_select(arel, selects)
       unless selects.empty?
         @implicit_readonly = false
-        # TODO: fix this ugly hack, we should refactor the callers to get an ARel compatible array.
-        # Before this change we were passing to ARel the last element only, and ARel is capable of handling an array
+        # TODO: fix this ugly hack, we should refactor the callers to get an Arel compatible array.
+        # Before this change we were passing to Arel the last element only, and Arel is capable of handling an array
         case select = selects.last
         when Arel::Expression, Arel::SqlLiteral
           arel.project(select)

railties/guides/source/api_documentation_guidelines.textile

@@ -29,7 +29,7 @@ Documentation has to be concise but comprehensive. Explore and document edge cas
 
 The proper names of Rails components have a space in between the words, like "Active Support". +ActiveRecord+ is a Ruby module, whereas Active Record is an ORM. Historically there has been lack of consistency regarding this, but we checked with David when docrails started. All Rails documentation consistently refer to Rails components by their proper name, and if in your next blog post or presentation you remember this tidbit and take it into account that'd be fenomenal :).
 
-Spell names correctly: HTML, MySQL, JavaScript, ERb. Use the article "an" for "SQL", as in "an SQL statement". Also "an SQLite database".
+Spell names correctly: Arel, HTML, MySQL, JavaScript, ERb. Use the article "an" for "SQL", as in "an SQL statement". Also "an SQLite database".
 
 h3. Example Code
 

railties/guides/source/initialization.textile

@@ -848,7 +848,7 @@ h5. +require "active_record"+
 
 TODO: Why are +activesupport_path+ and +activemodel_path+ defined here?
 
-The first three requires require ActiveSupport, Active Model and ARel in that order:
+The first three requires require ActiveSupport, Active Model and Arel in that order:
 
 <ruby>
   require 'active_support'