Improve YARD documentation

lib/mutant/delegator.rb

@@ -1,5 +1,7 @@
 module Mutant
+  # A simple delegator with opinions
   module Delegator
+    # Class level mixins
     module ClassMethods
 
     private

lib/mutant/expression.rb

@@ -20,6 +20,9 @@ module Mutant
     # Initialize expression
     #
     # @param [MatchData] match
+    #
+    # @api private
+    #
     def initialize(*)
       super
       @syntax = match.to_s
@@ -39,6 +42,8 @@ module Mutant
     #
     # @return [Fixnum]
     #
+    # @api private
+    #
     def match_length(neddle)
       if eql?(neddle)
         syntax.length

lib/mutant/mutator.rb

@@ -5,7 +5,10 @@ module Mutant
 
     # Run mutator on input
     #
-    # @param [Parser::AST::Node] node
+    # @param [Object] input
+    #   the input to mutate
+    #
+    # @param [Mutator] parent
     #
     # @return [self]
     #