[#102] Remove field name by default for newtypes in autodoc

Description

Problem: When implementing TypeHasDoc instance for newtypes, one has to make sure that he uses haskellRepNoFields, otherwise field name (unMyType) will be retained and in most cases this is not what we want.

Solution: Modify GTypeHasDoc implementation to make it remove field name for newtype by default.

Related issue(s)

Resolves #102 (closed)

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