Adjust docs to be in line with RSpec 4

Author: pirj

features/formatters/custom_formatter.feature

@@ -13,7 +13,7 @@ Feature: custom formatters
       """ruby
       class CustomFormatter
         # This registers the notifications this formatter supports, and tells
-        # us that this was written against the RSpec 3.x formatter API.
+        # us that this was written against the RSpec 4.x formatter API.
         RSpec::Core::Formatters.register self, :example_started
 
         def initialize(output)

lib/rspec/core/formatters.rb

@@ -164,7 +164,7 @@ def add(formatter_to_use, *paths)
 
         RSpec.warn_deprecation <<-WARNING.gsub(/\s*\|/, ' ')
           |The #{formatter_class} formatter uses the deprecated formatter
-          |interface not supported directly by RSpec 3.
+          |interface not supported directly by RSpec 4.
           |
           |To continue to use this formatter you must install the
           |`rspec-legacy_formatters` gem, which provides support

lib/rspec/core/project_initializer/spec/spec_helper.rb

@@ -27,8 +27,8 @@
   # library (such as bogus or mocha) by changing the `mock_with` option here.
   config.mock_with :rspec do |mocks|
     # Prevents you from mocking or stubbing a method that does not exist on
-    # a real object. This is generally recommended, and will default to
-    # `true` in RSpec 4.
+    # a real object. This is generally recommended, and is the default since
+    # RSpec 4.
     mocks.verify_partial_doubles = true
   end