Document support for response files

I believe that neither the [online documentation](https://ghc.gitlab.haskell.org/ghc/doc/users_guide/utils.html#writing-haskell-interfaces-to-c-code-hsc2hs) or the in-app documentation identify that `hsc2hs` now supports 'response files'.

There are references to 'response files' in the Change Log. However, the first mention (at 0.68.4) unfortunately has a URL that points to the wrong GHC issue.

The GHC User's Guide mentions that GHC supports ['GNU-style response files'](https://ghc.gitlab.haskell.org/ghc/doc/users_guide/using.html#command-line-arguments). However, if you google 'GNU response files' the first 'hit' is unhelpful: https://gcc.gnu.org/wiki/Response_Files - a 2008 wiki page suggesting it would be good if GCC followed what Windows compilers do. Microsoft provides: https://learn.microsoft.com/en-us/windows/win32/midl/response-files, but I could not identify (at least, not quickly) if GCC/GNU - and, consequently, hsc2hs, had adopted exactly what Microsoft documents.