nixos/make-options-doc: Fix declaration paths (#442917)

options = pivot(json.load(open(sys.argv[1 + optOffset], 'r')))

overrides = pivot(json.load(open(sys.argv[2 + optOffset], 'r')))

# fix up declaration paths in lazy options, since we don't eval them from a full nixpkgs dir

for (k, v) in options.items():

    # The _module options are not declared in nixos/modules

    if v.value['loc'][0] != "_module":

        v.value['declarations'] = list(map(lambda s: f'nixos/modules/{s}' if isinstance(s, str) else s, v.value['declarations']))

# merge both descriptions

for (k, v) in overrides.items():

    cur = options.setdefault(k, v).value