[ci skip] update guides to new version of rails 3.2.x
Merge pull request #14131 from kuldeepaggarwal/upgrade-rails-version

update guides to new version of rails 3.2.x, i.e. 3.2.17 [skip ci]
Fix Generation of proper migration when
    ActiveRecord::Base.pluralize_table_names = false.

    Previously, generation a migration like this:

        rails g migration add_column_name_to_user name

    would not generating the correct table name.