Update URL in reprs

[alimanfoo]

Point to better URL for Ag3 and Af1.

[leehart]

I believe this has already been done, e.g. https://github.com/malariagen/malariagen-data-python/blob/master/malariagen_data/af1.py has:

    def __repr__(self):
        text = (
            f"<MalariaGEN Af1 API client>\n"
            f"Storage URL             : {self._url}\n"
            f"Data releases available : {', '.join(self.releases)}\n"
            f"Results cache           : {self._results_cache}\n"
            f"Cohorts analysis        : {self._cohorts_analysis}\n"
            f"Site filters analysis   : {self._site_filters_analysis}\n"
            f"Software version        : malariagen_data {malariagen_data.__version__}\n"
            f"Client location         : {self.client_location}\n"
            f"---\n"
            f"Please note that data are subject to terms of use,\n"
            f"for more information see https://www.malariagen.net/data\n"
            f"or contact support@malariagen.net. For API documentation see \n"
            f"https://malariagen.github.io/malariagen-data-python/v{malariagen_data.__version__}/Af1.html"
        )
        return text

...which should point to the standard docs, e.g. https://malariagen.github.io/malariagen-data-python/v10.0.0/Af1.html