Fix a typo

`Rubocop::AST::Node` is a typo and is correctly `RuboCop::AST::Node`.

```console
% cd path/to/rubocop
% bin/console
irb(main):001:0> Rubocop::AST::Node
(irb):1:in `<main>': uninitialized constant Rubocop (NameError)
Did you mean?  RuboCop
from bin/console:10:in `<main>'
irb(main):002:0> RuboCop::AST::Node
=> RuboCop::AST::Node
```

https://github.com/rubocop/rubocop-ast/blob/v1.7.0/lib/rubocop/ast/node.rb

lib/rubocop/cop/corrector.rb

@@ -32,7 +32,7 @@ def initialize(source)
 
       # Removes `size` characters prior to the source range.
       #
-      # @param [Parser::Source::Range, Rubocop::AST::Node] range or node
+      # @param [Parser::Source::Range, RuboCop::AST::Node] range or node
       # @param [Integer] size
       def remove_preceding(node_or_range, size)
         range = to_range(node_or_range)
@@ -44,7 +44,7 @@ def remove_preceding(node_or_range, size)
       # If `size` is greater than the size of `range`, the removed region can
       # overrun the end of `range`.
       #
-      # @param [Parser::Source::Range, Rubocop::AST::Node] range or node
+      # @param [Parser::Source::Range, RuboCop::AST::Node] range or node
       # @param [Integer] size
       def remove_leading(node_or_range, size)
         range = to_range(node_or_range)
@@ -56,7 +56,7 @@ def remove_leading(node_or_range, size)
       # If `size` is greater than the size of `range`, the removed region can
       # overrun the beginning of `range`.
       #
-      # @param [Parser::Source::Range, Rubocop::AST::Node] range or node
+      # @param [Parser::Source::Range, RuboCop::AST::Node] range or node
       # @param [Integer] size
       def remove_trailing(node_or_range, size)
         range = to_range(node_or_range)
@@ -90,7 +90,7 @@ def to_range(node_or_range)
                 else
                   raise TypeError,
                         'Expected a Parser::Source::Range, Comment or ' \
-                        "Rubocop::AST::Node, got #{node_or_range.class}"
+                        "RuboCop::AST::Node, got #{node_or_range.class}"
                 end
         validate_buffer(range.source_buffer)
         range

spec/rubocop/cop/corrector_spec.rb

@@ -73,7 +73,7 @@ def do_rewrite(corrections = nil, &block)
       expect do
         do_rewrite { |corr| corr.replace(1..3, 'oops') }
       end.to raise_error(TypeError, 'Expected a Parser::Source::Range, '\
-                                    'Comment or Rubocop::AST::Node, got Range')
+                                    'Comment or RuboCop::AST::Node, got Range')
     end
 
     context 'when range is from incorrect source' do