message: cleanup: generator.py words correction.
diff: @@ -246,7 +246,7 @@ class FieldSpec:
  def is_nullable_in_version(self, version):
  """
  - Whether thie field is nullable in given version.
  + Whether the field is nullable in given version.
  Fields can be non-nullable in earlier versions.
  See https://github.com/apache/kafka/tree/2.2.0-rc0/clients/src/main/resources/common/message#nullable-fields
  """
  @@ -435,7 +435,7 @@ class Complex(TypeSpecification):
  def __compute_declaration_chain(self):
  """
  - Computes all dependendencies, what means all non-primitive types used by this type.
  + Computes all dependencies, what means all non-primitive types used by this type.
  They need to be declared before this struct is declared.
  """
  result = []
  