Add descriptive comments for rubocop-rspec cops

[ci skip]

.rubocop.yml

@@ -1076,22 +1076,30 @@ Rails/Validation:
 
 ##################### RSpec ##################################
 
+# Check that instances are not being stubbed globally.
 RSpec/AnyInstance:
   Enabled: false
 
+# Check that the first argument to the top level describe is the tested class or
+# module.
 RSpec/DescribeClass:
   Enabled: false
 
+# Use `described_class` for tested class / module.
 RSpec/DescribeMethod:
   Enabled: false
 
+# Checks that the second argument to top level describe is the tested method
+# name.
 RSpec/DescribedClass:
   Enabled: false
 
+# Checks for long example.
 RSpec/ExampleLength:
   Enabled: false
   Max: 5
 
+# Do not use should when describing your tests.
 RSpec/ExampleWording:
   Enabled: false
   CustomTransform:
@@ -1100,24 +1108,30 @@ RSpec/ExampleWording:
     not: does not
   IgnoredWords: []
 
+# Checks the file and folder naming of the spec file.
 RSpec/FilePath:
   Enabled: false
   CustomTransform:
     RuboCop: rubocop
     RSpec: rspec
 
+# Checks if there are focused specs.
 RSpec/Focus:
   Enabled: true
 
+# Checks for the usage of instance variables.
 RSpec/InstanceVariable:
   Enabled: false
 
+# Checks for multiple top-level describes.
 RSpec/MultipleDescribes:
   Enabled: false
 
+# Enforces the usage of the same method on all negative message expectations.
 RSpec/NotToNot:
   EnforcedStyle: not_to
   Enabled: false
 
+# Prefer using verifying doubles over normal doubles.
 RSpec/VerifiedDoubles:
   Enabled: false