[DOC] Fix hash style in Hash#flatten

Author: peterzhu2118

hash.c

@@ -4492,21 +4492,21 @@ flatten_i(VALUE key, VALUE val, VALUE ary)
  *  Examples; note that entry <tt>foo: {bar: 1, baz: 2}</tt> is never flattened.
  *
  *   h = {foo: {bar: 1, baz: 2}, bat: [:bam, [:bap, [:bah]]]}
- *   h.flatten(1) # => [:foo, {:bar=>1, :baz=>2}, :bat, [:bam, [:bap, [:bah]]]]
- *   h.flatten(2) # => [:foo, {:bar=>1, :baz=>2}, :bat, :bam, [:bap, [:bah]]]
- *   h.flatten(3) # => [:foo, {:bar=>1, :baz=>2}, :bat, :bam, :bap, [:bah]]
- *   h.flatten(4) # => [:foo, {:bar=>1, :baz=>2}, :bat, :bam, :bap, :bah]
- *   h.flatten(5) # => [:foo, {:bar=>1, :baz=>2}, :bat, :bam, :bap, :bah]
+ *   h.flatten(1) # => [:foo, {bar: 1, baz: 2}, :bat, [:bam, [:bap, [:bah]]]]
+ *   h.flatten(2) # => [:foo, {bar: 1, baz: 2}, :bat, :bam, [:bap, [:bah]]]
+ *   h.flatten(3) # => [:foo, {bar: 1, baz: 2}, :bat, :bam, :bap, [:bah]]
+ *   h.flatten(4) # => [:foo, {bar: 1, baz: 2}, :bat, :bam, :bap, :bah]
+ *   h.flatten(5) # => [:foo, {bar: 1, baz: 2}, :bat, :bam, :bap, :bah]
  *
  *  With negative integer +depth+,
  *  flattens all levels:
  *
- *    h.flatten(-1) # => [:foo, {:bar=>1, :baz=>2}, :bat, :bam, :bap, :bah]
+ *    h.flatten(-1) # => [:foo, {bar: 1, baz: 2}, :bat, :bam, :bap, :bah]
  *
  *  With +depth+ zero,
  *  returns the equivalent of #to_a:
  *
- *    h.flatten(0) # => [[:foo, {:bar=>1, :baz=>2}], [:bat, [:bam, [:bap, [:bah]]]]]
+ *    h.flatten(0) # => [[:foo, {bar: 1, baz: 2}], [:bat, [:bam, [:bap, [:bah]]]]]
  *
  *  Related: see {Methods for Converting}[rdoc-ref:Hash@Methods+for+Converting].
  */