Update release notes with AR::Relation#inspect change [ci skip]

See 07314e64.
Also fix some tabs in AR Changelog.

activerecord/CHANGELOG.md

@@ -2,11 +2,11 @@
 
 *   Add `add_reference` and `remove_reference` schema statements. Aliases, `add_belongs_to`
     and `remove_belongs_to` are acceptable. References are reversible.
-		Examples:
+    Examples:
 
         # Create a user_id column
         add_reference(:products, :user)
-				# Create a supplier_id, supplier_type columns and appropriate index
+        # Create a supplier_id, supplier_type columns and appropriate index
         add_reference(:products, :supplier, polymorphic: true, index: true)
         # Remove polymorphic reference
         remove_reference(:products, :supplier, polymorphic: true)
@@ -867,7 +867,7 @@
 
 *   LRU cache in mysql and sqlite are now per-process caches.
 
-    * lib/active_record/connection_adapters/mysql_adapter.rb: LRU cache  	  keys are per process id.
+    * lib/active_record/connection_adapters/mysql_adapter.rb: LRU cache     keys are per process id.
     * lib/active_record/connection_adapters/sqlite_adapter.rb: ditto
     *Aaron Patterson*
 

guides/source/4_0_release_notes.textile

@@ -350,11 +350,14 @@ column_exists?(:testings, :taggable_id, :integer, null: false)
 column_exists?(:testings, :taggable_type, :string, default: 'Photo')
 </ruby>
 
-* <tt>ActiveRelation#inspect</tt> no longer calls <tt>#to_a</tt>. This means that in places where <tt>#inspect</tt> is implied (such as in the console), creating a relation will not execute it anymore, you'll have to call <tt>#to_a</tt> when necessary:
+* <tt>ActiveRecord::Relation#inspect</tt> now makes it clear that you are dealing with a <tt>Relation</tt> object rather than an array:
 
 <ruby>
-User.where(:age => 30)      # => returns the relation
-User.where(:age => 30).to_a # => executes the query and returns the loaded objects, as before
+User.where(:age => 30).inspect
+# => <ActiveRecord::Relation [#<User ...>, #<User ...>]>
+
+User.where(:age => 30).to_a.inspect
+# => [#<User ...>, #<User ...>]
 </ruby>
 
 * Add <tt>:collation</tt> and <tt>:ctype</tt> support to PostgreSQL. These are available for PostgreSQL 8.4 or later.