resources :posts, :path => "/admin"

would route "/admin/posts" to the PostsController but it actually routed "/admin" to the PostsController

Mention the case that `render` will return nil if given `:collection` is nil or empty when rendering partial.

i18n guide: remove link to external page about 'How to encode the current locale in the URL' as it no longer exists

i18n guide: it's activerecord.errors.messages.record_invalid (instead of 'invalid'), and messagges typo

remove old school validations and replaced with new validates method. Pending: fix active_record guide

Signed-off-by: NJosé Valim <jose.valim@gmail.com>

class inheritable attributes is used no more! all internal use of class inheritable has been changed to class_attribute. class inheritable attributes has been deprecated.
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

Mention the case that `render` will return nil if given `:collection` is nil or empty when rendering partial.

* Examples running with the text are preferred over separate Example
  sections.
* No need to call puts, in # => we show the return value, not STDOUT.
* Say explicitly that double quotes are removed.
* Specify that we are talking \uXXX, rather than, say, HTML entities.