Make Style/AccessModifierDeclarations disabled by default

Follow up of rubocop#5953, rubocop#6032

I think it is too difficult to enforce `group` (default) style
by default because it doesn't work for some methods.

For example, `def_delegator` doesn't work when using `group` style:

```ruby
require 'forwardable'

class Cat
  def meow
    puts "Meow!"
  end
end

class CatCage
  extend Forwardable

  def initialize(cat)
    @cat = cat
  end

  private

  def_delegator :@cat, :meow
end
```

```
[8] pry(main)> CatCage.new(Cat.new).meow
Meow!
=> nil
```

This is because `def_delegator` defines a method by `self.module_eval`.
Forcing group styles by default may be misleading for the above problems.

Maybe it is needed to add such methods to the whitelist and exclude
them from inspection, but it seems to be difficult for me.

First of all, I think it should make this cop disabled by default
and help users confused by this cop. WDYT? @brandonweiss

CHANGELOG.md

@@ -30,6 +30,7 @@
 * [#5990](https://github.com/bbatsov/rubocop/pull/5990): Drop support for MRI 2.1. ([@drenmi][])
 * [#3299](https://github.com/bbatsov/rubocop/issues/3299): `Lint/UselessAccessModifier` now warns when `private_class_method` is used without arguments. ([@Darhazer][])
 * [#6026](https://github.com/rubocop-hq/rubocop/pull/6026): Exclude `refine` by default from `Metrics/BlockLength` cop. ([@kddeisz][])
+* [#6066](https://github.com/rubocop-hq/rubocop/pull/6066): Make `Style/AccessModifierDeclarations` disabled by default. ([@wata727][])
 
 ## 0.57.2 (2018-06-12)
 

config/disabled.yml

@@ -52,6 +52,10 @@ Rails/SaveBang:
   StyleGuide: 'https://github.com/rubocop-hq/rails-style-guide#save-bang'
   Enabled: false
 
+Style/AccessModifierDeclarations:
+  Description: 'Checks style of how access modifiers are used.'
+  Enabled: false
+
 Style/AutoResourceCleanup:
   Description: 'Suggests the usage of an auto resource cleanup version of a method (if available).'
   Enabled: false

config/enabled.yml

@@ -1336,10 +1336,6 @@ Security/YAMLLoad:
 
 #################### Style ###############################
 
-Style/AccessModifierDeclarations:
-  Description: 'Checks style of how access modifiers are used.'
-  Enabled: true
-
 Style/Alias:
   Description: 'Use alias instead of alias_method.'
   StyleGuide: '#alias-method'

manual/cops_style.md

@@ -4,7 +4,7 @@
 
 Enabled by default | Supports autocorrection
 --- | ---
-Enabled | No
+Disabled | No
 
 Access modifiers should be declared to apply to a group of methods
 or inline before each method, depending on configuration.