Added documentation to explain what happens if you don't set any values for...

Added documentation to explain what happens if you don't set any values for the dependent option on has_many

activerecord/lib/active_record/associations.rb

@@ -1097,13 +1097,16 @@ module ClassMethods
       #   alongside this object by calling their +destroy+ method. If set to <tt>:delete_all</tt> all associated
       #   objects are deleted *without* calling their +destroy+ method. If set to <tt>:nullify</tt> all associated
       #   objects' foreign keys are set to +NULL+ *without* calling their +save+ callbacks. If set to
-      #   <tt>:restrict</tt> an error will be added to the object, preventing its deletion, if any associated 
+      #   <tt>:restrict</tt> an error will be added to the object, preventing its deletion, if any associated
       #   objects are present.
       #
       #   If using with the <tt>:through</tt> option, the association on the join model must be
       #   a +belongs_to+, and the records which get deleted are the join records, rather than
       #   the associated records.
       #
+      #   If you don't set any values, all associated objects remain untouched and with an invalid
+      #   foreign key.
+      #
       # [:finder_sql]
       #   Specify a complete SQL statement to fetch the association. This is a good way to go for complex
       #   associations that depend on multiple tables. May be supplied as a string or a proc where interpolation is
@@ -1382,7 +1385,7 @@ def has_one(name, options = {})
       #   and +decrement_counter+. The counter cache is incremented when an object of this
       #   class is created and decremented when it's destroyed. This requires that a column
       #   named <tt>#{table_name}_count</tt> (such as +comments_count+ for a belonging Comment class)
-      #   is used on the associate class (such as a Post class) - that is the migration for 
+      #   is used on the associate class (such as a Post class) - that is the migration for
       #   <tt>#{table_name}_count</tt> is created on the associate class (such that Post.comments_count will
       #   return the count cached, see note below). You can also specify a custom counter
       #   cache column by providing a column name instead of a +true+/+false+ value to this